Systems & Network Administrators

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Technical Interview Questions – Networking

1. What is an IP address?2. What is a subnet mask?3. What is ARP?4. What is ARP Cache Poisoning?

5. What is the ANDing process?6. What is a default gateway? What happens if I don't have one?7. Can a workstation computer be configured to browse the

Internet and yet NOT have a default gateway?8. What is a subnet?9. What is APIPA?10. What is an RFC? Name a few if possible (not necessarily

the numbers, just the ideas behind them)11. What is RFC 1918?12. What is CIDR?13. You have the following Network ID: 192.115.103.64/27.

What is the IP range for your network?14. You have the following Network ID: 131.112.0.0. You need

at least 500 hosts per network. How many networks can youcreate? What subnet mask will you use?15. You need to view at network traffic. What will you use?

Name a few tools16. How do I know the path that a packet takes to the

destination?17. What does the ping 192.168.0.1 -l 1000 -n 100 command do?18. What is DHCP? What are the benefits and drawbacks of

using it?19. Describe the steps taken by the client and DHCP server

in order to obtain an IP address.20. What is the DHCPNACK and when do I get one? Name 2

scenarios.21. What ports are used by DHCP and the DHCP clients?22. Describe the process of installing a DHCP server in an

AD infrastructure.23. What is DHCPINFORM?24. Describe the integration between DHCP and DNS.25. What options in DHCP do you regularly use for an MS

network?26. What are User Classes and Vendor Classes in DHCP?27. How do I configure a client machine to use a specific

User Class?28. What is the BOOTP protocol used for, where might you

find it in Windows network infrastructure?29. DNS zones – describe the differences between the 4 types.30. DNS record types – describe the most important ones.31. Describe the process of working with an external domain

name32. Describe the importance of DNS to AD.33. Describe a few methods of finding an MX record for a

remote domain on the Internet.34. What does "Disable Recursion" in DNS mean?35. What could cause the Forwarders and Root Hints to be

grayed out?36. What is a "Single Label domain name" and what sort of

issues can it cause?37. What is the "in-addr.arpa" zone used for?38. What are the requirements from DNS to support AD?39. How do you manually create SRV records in DNS?

40. Name 3 benefits of using AD-integrated zones.41. What are the benefits of using Windows 2003 DNS when



using AD-integrated zones?42. You installed a new AD domain and the new (and first) DC

has not registered its SRV records in DNS. Name a few possible causes.

43. What are the benefits and scenarios of using Stub zones?44. What are the benefits and scenarios of using Conditional

Forwarding?45. What are the differences between Windows Clustering, Network Load Balancing and Round Robin, and scenarios foreach use?

46. How do I work with the Host name cache on a clientcomputer?

47. How do I clear the DNS cache on the DNS server?48. What is the 224.0.1.24 address used for?49. What is WINS and when do we use it?50. Can you have a Microsoft-based network without any WINS

server on it? What are the "considerations" regarding notusing WINS?

51. Describe the differences between WINS push and pull

replications.52. What is the difference between tombstoning a WINS record and simply deleting it?

53. Name the NetBIOS names you might expect from a Windows2003 DC that is registered in WINS.

54. Describe the role of the routing table on a host and ona router.

55. What are routing protocols? Why do we need them? Name a few.56. What are router interfaces? What types can they be?57. In Windows 2003 routing, what are the interface filters?58. What is NAT?59. What is the real difference between NAT and PAT?60. How do you configure NAT on Windows 2003?61. How do you allow inbound traffic for specific hosts on Windows 2003

NAT?62. What is VPN? What types of VPN does Windows 2000 and

beyond work with natively?63. What is IAS? In what scenarios do we use it?64. What's the difference between Mixed mode and Native mode

in AD when dealing with RRAS?65. What is the "RAS and IAS" group in AD?66. What are Conditions and Profile in RRAS Policies?67. What types or authentication can a Windows 2003 based

RRAS work with?68. How does SSL work?69. How does IPSec work?70. How do I deploy IPSec for a large number of computers?71. What types of authentication can IPSec use?72. What is PFS (Perfect Forward Secrecy) in IPSec?73. How do I monitor IPSec?74. Looking at IPSec-encrypted traffic with a sniffer. What

packet types do I see?75. What can you do with NETSH?76. How do I look at the open ports on my machine?

1) What is an IP address?

This definition is based on Internet Protocol Version 4.

See Internet Protocol Version 6 (IPv6) for a description ofthe newer 128-bit IP address. Note that the system of IP



address classes described here, while forming the basis forIP address assignment, is generally bypassed today by useof Classless Inter-Domain Routing (CIDR) addressing.In the most widely installed level of the Internet Protocol(IP) today, an IP address is a 32-bit number thatidentifies each sender or receiver of information that issent in packets across the Internet. When you request anHTML page or send e-mail, the Internet Protocol part ofTCP/IP includes your IP address in the message (actually,in each of the packets if more than one is required) andsends it to the IP address that is obtained by looking upthe domain name in the Uniform Resource Locator yourequested or in the e-mail address you're sending a noteto. At the other end, the recipient can see the IP addressof the Web page requestor or the e-mail sender and canrespond by sending another message using the IP address itreceived.

An IP address has two parts: the identifier of a particularnetwork on the Internet and an identifier of the particulardevice (which can be a server or a workstation) within thatnetwork. On the Internet itself - that is, betweentherouter that move packets from one point to another alongthe route - only the network part of the address is lookedat.

2) What is a subnet mask?

A subnet mask allows you to identify which part of an IPaddress is reserved for the network, and which part isavailable for host use. If you look at the IP addressalone, especially now with classless inter-domain routing,you can't tell which part of the address is which. Addingthe subnet mask, or netmask, gives you all the informationyou need to calculate network and host portions of theaddress with ease. In summary, knowing the subnet mask canallow you to easily calculate whether IP addresses are onthe same subnet, or not.

3) What is ARP?

ARP is a very important part of IP networking. ARP is used

to connect OSI Layer 3 (Network) to OSI Layer 2 (Data-Link). For most of us, that means that ARP is used to linkour IP addressing to our Ethernet addressing (MACAddressing). For you to communicate with any device on yournetwork, you must have the Ethernet MAC address for thatdevice. If the device is not on your LAN, you go throughyour default gateway (your router). In this case, yourrouter will be the destination MAC address that your PCwill communicate with.

4) What is ARP Cache Poisoning?

ARP cache poisoning, also known as ARP spoofing, is the

process of falsifying the source Media Access Control (MAC)addresses of packets being sent on an Ethernet network. Itis a MAC layer attack that can only be carried out when an



attacker is connected to the same local network as thetarget machines, limiting its effectiveness only tonetworks connected with switches, hubs, and bridges; notrouters.

5) What is the ANDing process?

Notice that when the resulting AND values are convertedback to binary, it becomes clear that the two hosts are ondifferent networks. Computer A is on subnet 192.168.56.0,while the destination host is on subnet 192.168.64.0, whichmeans that Computer A will next be sending the data to arouter. Without ANDing, determining local and remote hostscan be difficult. Once you’re very familiar with subnetting and calculating ranges of addresses, recognizing local andremote hosts will become much more intuitive.Whenever you’re in doubt as to whether hosts are local or remote, use the ANDing process. You should also notice thatthe ANDing process always produces the subnet ID of a givenhost.

6) What is a default gateway? What happens if I don't have one?

In computer networking, a default network gateway is thedevice that passes traffic from the local subnet to deviceson other subnets. The default gateway often connects alocal network to the Internet, although internal gatewaysfor connecting two local networks also exist.Can a workstation computer be configured to browse theInternet and yet NOT have a default gateway?

7) Can a workstation computer be configured to browse theInternet and yet NOT have a default gateway?

If we are using public ip address, we can browse theinternet. If it is having an intranet address a gatewayis needed as a router or firewall to communicate with internet.

8) What is a subnet?

A subnet is a logical organization of network address rangesused to separate hosts and network devices from each otherto serve a design purpose.In many cases, subnets are created to serve as physical or

geographical separations similar to those found betweenrooms, floors, buildings, or cities.

9) What is APIPA?

Short for Automatic Private IP Addressing, a feature oflater Windows operating systems. With APIPA, DHCP clientscan automatically self-configure an IP address and subnetmask when a DHCPserver isn't available. When a DHCP clientboots up, it first looks for a DHCP server in order toobtain an IP address and subnet mask. If the client isunable to find the information, it uses APIPA toautomatically configure itself with an IP address from a

range that has been reserved especially for Microsoft. TheIP address range is 169.254.0.1 through 169.254.255.254.The client also configures itself with a default class B



subnet mask of 255.255.0.0. A client uses the self-configured IP address until a DHCP server becomesavailable.The APIPA service also checks regularly for the presence ofa DHCP server (every five minutes, according to Microsoft).If it detects a DHCP server on the network, APIPA stops,and the DHCP server replaces the APIPA networking addresseswith dynamically assigned addresses.

APIPA is meant for nonrouted small business environments,usually less than 25 clients.

10) What is an RFC? Name a few if possible (not necessarily thenumbers, just the ideas behind them)

Short for Request for Comments, a series of notes about theInternet, started in 1969 (when the Internet was theARPANET). An Internet Document can be submitted to the IETFby anyone, but the IETF decides if the document becomes anRFC. Eventually, if it gains enough interest, it may evolveinto an Internet standard.Each RFC is designated by an RFC number. Once published, anRFC never changes. Modifications to an original RFC areassigned a new RFC number.

11) What is RFC 1918?

RFC 1918 is Address Allocation for Private Internets TheInternet Assigned Numbers Authority (IANA) has reserved thefollowing three blocks of theIP address space for private internets: 10.0.0.0 -10.255.255.255 (10/8 prefix) 172.16.0.0 - 172.31.255.255(172.16/12 prefix) 192.168.0.0 - 192.168.255.255(192.168/16 prefix) We will refer to the first block as"24-bit block", the second as "20-bit block", and to thethird as "16-bit" block. Note that(in pre-CIDR notation) the first block is nothing but asingle class A network number, while the second block is aset of 16 contiguous class B networknumbers, and third block is a set of 256 contiguous class Cnetwork numbers.

12) What is CIDR?

CIDR (Classless Inter-Domain Routing, sometimes known assupernetting) is a way to allocate and specify the Internetaddresses used in inter-domainrouting more flexibly than with the original system ofInternet Protocol (IP) address classes. As a result, thenumber of available Internet addresseshas been greatly increased.



13. You have the following Network ID:

192.115.103.64/27.What is the IP range for your network?

It ranges from 192.115.103.64 - 192.115.103.96But the usable address are from 192.115.103.64 -192.115.103.94192.115.103.95 - it is the broadcast address192.115.103.96 - will be the ip address of next range

we can use 30 hostes in this network

14.You have the following Network ID: 131.112.0.0. You need at least 500 hosts per network. How many networks can youcreate? What subnet mask will you use?

If you need 500 users then 2^9th would give you 512(remember the first and last are network and broadcast), 510usable. So of your 32 bits you would turn the last 9 off for hostand that would give you give you a 255.255.254.0 subnet mask(11111111.11111111.11111110.00000000). Now that we know thatwe can see that you have the first 7 of your third octet turned onso to figure out how many subnets you have us the formula2^7th= 128. So you can have 128 subnets with 500 people on them.

15.You need to view at network traffic. What will you use?

Name a few tools

winshark or tcp dump

16. How do I know the path that a packet takes to the destination?

use "tracert" command-line

17. What does the ping 192.168.0.1 -l 1000 -n 100 command do?

The ping command will send roundtrip packets to a destination (other PC, router, printer, etc. ) and see how long it takes. The192.168.0.1 is the destination ( which, by the way is a typicaldefault IP address of a router. ) The -l 1000 is how big the packetshould be in bytes.

The default is 32, if the -l parameter is not used. And the

-n 100 is saying to send it 100 times. The default is 4,when thisparameter is not used.

18. What is DHCP? What are the benefits and drawbacks of using it?

Benefits:

1. DHCP minimizes configuration errors caused by manual IP addressconfigurationDHCP minimizes configuration errors caused by manual IPaddress configuration



2. Reduced network administration.

Disadvantage

Your machine name does not change when you get a new IP address. TheDNS (Domain Name System) name is associated with your IP address andtherefore does change. This only presents a problem if other clientstry to access your machine by its DNS name.

Benefits:

1. DHCP minimizes configuration errors caused by manual IP addressconfigurationDHCP minimizes configuration errors caused by manual IPaddress configuration

2. Reduced network administration.

Disadvantage

Your machine name does not change when you get a new IPaddress. The DNS (Domain Name System) name is associatedwith your IP address and therefore doeschange. This only presents a problem if other clients try toaccess your machine by its DNS name.

19.Describe the steps taken by the client and DHCP server in orderto obtain an IP address.

* At least one DHCP server must exist on a network.Once the DHCP server software is installed, you create aDHCP scope, which is a pool of IP addresses that the server manages.When clients log on, they request an IP address from the server, andthe server provides an IP address from its pool of availableaddresses.

* DHCP was originally defined in RFC 1531 (Dynamic HostConfiguration Protocol, October 1993) but the most recentupdate is RFC 2131 (Dynamic Host Configuration Protocol, March1997). The IETF Dynamic Host Configuration (dhc) Working Group ischartered to produce a protocol for automated allocation,configuration, and management of IP addresses and TCP/IP protocol

stack parameters.

20. What is the DHCPNACK and when do I get one? Name 2scenarios.

DHCP server issues a NAK to DHCP clients.For simplificationpurposes, I am listing down the possible scenarios in whichthe server should NOT issue a NAK. This should give you agood understanding of DHCP NAK behavior.When a DHCP server receivesa DHCPRequest with a previously assigned address specified, itfirst checks to see if it came from the local segment by

checking the GIADDR field. If it originated from the local segment,



the DHCP server compares the requested address to the IP address andsubnet mask belonging to the local interface that received therequest. DHCP server will issue a NAK to the client ONLY IF it issure that the client, "on the local subnet", is asking foran address that doesn't exist on that subnet.The server will send aNAK EXCEPT in the following scenarios:-

1. Requested address from possibly the same subnet but not in theaddress pool of the server:- This can be the failover scenario inwhich 2 DHCP servers are serving the same subnet so that when onegoes down, the other should not NAK to clients which got an IP fromthe first server.

2. Requested address on a different subnet:-If the Address is from the same superscope to which thesubnet belongs, DHCP server will ACK the REQUEST.

21. What ports are used by DHCP and the DHCP clients?

Requests are on UDP port 68, Server replies on UDP 67

22. Describe the process of installing a DHCP server in an ADinfrastructure.

It is about how to install DHCP server...In Windows server 2008 ...Go to... START-->Administrative Tools --> Server Manager -->Roles (Right Click)--> Add Roles (Here a Add roles wizard will appear) -->Check the box of DHCP Server--> click next --> Next --> In IPv4 DNS settings Give theparent domain Name and DNS serverIP address and validate it... Click Next --> Add the DHCPscopes --> Disable DHCPv6.. clickNext --> Finally Click on INSTALLThis was the process for installing the DHCP server.,....

23. What is DHCPINFORM?

DHCPInform is a DHCP message used by DHCP clients to obtainDHCP options. While PPP remote access clients do not useDHCP to obtain IP addresses for theremote access connection, Windows 2000 and Windows 98 remote

access clients use the DHCPInform message to obtain DNSserver IP addresses, WINS serverIP addresses, and a DNS domain name. The DHCPInform messageis sent after the IPCP negotiation is concluded.The DHCPInform message received by the remote access serveris then forwarded to a DHCP server. The remote access serverforwards DHCPInform messages onlyif it has been configured with the DHCP Relay Agent..

24. Describe the integration between DHCP and DNS.

Traditionally, DNS and DHCP servers have been configured andmanaged one at a time. Similarly, changing authorization

rights for a particular user on agroup of devices has meant visiting each one and makingconfiguration changes. DHCP integration with DNS allows the



aggregation of these tasks acrossdevices, enabling a company's network services to scale instep with the growth of network users, devices, andpolicies, while reducing administrativeoperations and costs.

This integration provides practical operational efficienciesthat lower total cost of ownership. Creating a DHCP networkautomatically creates an associatedDNS zone, for example, reducing the number of tasks requiredof network administrators. And integration of DNS and DHCPin the same database instanceprovides unmatched consistency between service andmanagement views of IP address-centric network services data.

25.What options in DHCP do you regularly use for an MSnetwork?

Automatic providing IP address

Subnet mask

DNS server

Domain name

Default getaway or router

26. What are User Classes and Vendor Classes in DHCP?

Microsoft Vendor Classes

The following list contains pre-defined vendor classes thatare available in Windows 2000 DHCP server.

Collapse this tableExpand this table

Class Data Class Name Description MSFT 5.0 Microsoft Windows2000 options Class that includes all Windows 2000 DHCPclients. MSFT 98 MicrosoftWindows 98 options Class that includes all Windows 98 andMicrosoft Windows Millennium Edition (Me) DHCP clients. MSFTMicrosoft options Class that includes

all Windows 98, Windows Me, and Windows 2000 DHCP clients.If you have non-Microsoft DHCP clients, you can define othervendor-specific classes on the DHCP server. When you definesuch classes, make sure the vendorclass identifier that you define matches the identifier usedby the clients.

Back to the top

User Classes

The following list contains pre-defined user classes that

are available in Windows 2000 DHCP server.

Collapse this tableExpand this table



Class ID Class Type Description Unspecified Default userclass All DHCP clients that have no user class specified.RRAS.Microsoft DefaultRouting and Remote Access class All Dial-Up Networking (DUN)clients. Bootp Default Bootp class All Bootp clients

In addition to these pre-defined classes, you can also addcustom user classes for Windows 2000 DHCP clients. When youconfigure such classes, you mustspecify a custom identifier that corresponds to the userclass defined on the DHCP server.

27.How do I configure a client machine to use a specificUser Class?

The command to configure a client machine to use a specificuser class is

ipconfig /setclassid "<Name of your Network card>" <Name ofthe class you created on DHCP and you want to join (Name iscase sensitive)>

Eg:

ipconfig /setclassid " Local Area Network" Accounting

28. What is the BOOTP protocol used for, where might youfind it in Windows network infrastructure?

ootP (RFC951) provides

* a unique IP address to the requester (using port 67)similar to the DHCP request on port 68 AND

* can provide (where supported) the ability to boot asystem without a hard drive (ie: a diskless client)

Apple OS X 10.* Server supports BootP (albeit) renamed asNetBoot. The facility allows the Admin to maintain aselected set of configurations as bootimages and then assign sets of client systems to share(orboot from) that image. For example Accounting, Management,

and Engineering departments haveelements in common, but which can be unique from otherdepartments. Performing upgrades and maintenance on threeimages is far more productive that workingon all client systems individually.

Startup is obviously network intensive, and beyond 40-50clients, the Admin needs tocarefully subnet the infrastructure, use gigabit switches,and host the images local to the clients to avoid saturatingthe network. This will expand thenumber of BootP servers and multiply the number of images,

but the productivity of 1 BootP server per 50 clients isundeniable :)



Sunmicro, Linux, and AIX RS/600 all support BootP.

Todate, Windows does not support booting "diskless clients".

29. DNS zones – describe the differences between the 4 types.

Dns zone is actual file which contains all the records for aspecific domain.

i)Forward Lookup Zones :-

This zone is responsible to resolve host name to ip.

ii)Reverse Lookup Zones :-

This zone is responsible to resolve ip to host name.

iii)Stub Zone :-

Stubzone is read only copy of primary zone.but it containsonly 3 records viz

the SOA for the primary zone, NS record and a Host (A) record.

30. DNS record types – describe the most important ones.Type of Record What it does

A (Host) Classic resource record. Maps hostname to IP(ipv4)

PTR Maps IP to hostname (Reverse of A (Host)

AAAA Maps hostname to ip (ipv6)

Cname Canonical name, in plain English an alias.such as

Web Server,FTP Server, Chat Server

NS Identifies DNS name servers. Important for forwarders

MX Mail servers, particularly for other domains.MX records

required to deliver internet email.

_SRV Required for Active Directory. Whole family of

underscore service,records, for example, gc = global catalog.

SOA Make a point of finding the Start of Authority (SOA) tabat the

DNS Server.

31. Describe the process of working with an external domain name

Serving Sites with External Domain Name Servers



If you host Web sites on this server and have a standaloneDNS server acting as a primary (master) name server for yoursites, you may want to set up your control panel's DNSserver to function as a secondary (slave) name server:

To make the control panel's DNS server act as a secondaryname server:

1. Go to Domains > domain name > DNS Settings (in the WebSite group).

2. Click Switch DNS Service Mode.3. Specify the IP address of the primary (master) DNS server.4. Click Add.5. Repeat steps from 1 to 5 for each Web site that needs

to have a secondary name server on this machine.

To make the control panel's DNS server act as a primary fora zone:


2. Click Switch DNS Service Mode. The original resourcerecords for the zone will be restored.

If you host Web sites on this server and rely entirely onother machines to perform the Domain Name Service for yoursites (there are two external name servers - a primary and asecondary), switch off the control panel's DNS service foreach site served by external name servers.

To switch off the control panel's DNS service for a siteserved by an external name server:


2. Click Switch Off the DNS Service in the Tools group.Turning the DNS service off for the zone will refresh thescreen, so that only a list of name servers remains.

Note: The listed name server records have no effect on thesystem. They are only presented on the screen as clickable

links to give you a chance to validate the configuration ofthe zone maintained on the external authoritative name servers.

1. Repeat the steps from 1 to 3 to switch off the localdomain name service for each site served by external nameservers.

If you wish to validate the configuration of a zonemaintained on authoritative name servers:


2. Add to the list the entries pointing to theappropriate name servers that are authoritative for thezone: click Add, specify a name server, and click OK. Repeat



this for each name server you would like to test.

The records will appear in the list.

1. Click the records that you have just created.Parallels Plesk Panel will retrieve the zone file from aremote name server and check the resource records to makesure that domain's resources are properly resolved.

The results will be interpreted and displayed on the screen.

32. Describe the importance of DNS to AD.

When you install Active Directory on a server, you promotethe server to the role of a domain controller for aspecified domain. When completing thisprocess, you are prompted to specify a DNS domain name forthe Active Directory domain for which you are joining andpromoting the server.If during thisprocess, a DNS server authoritative for the domain that youspecified either cannot be located on the network or doesnot support the DNS dynamic updateprotocol, you are prompted with the option to install a DNSserver. This option is provided because a DNS server isrequired to locate this server or otherdomain controllers for members of an Active Directory domain

33.Describe a few methods of finding an MX record for aremote domain on the Internet.

In order to find MX Records for SMTP domains you can useCommand-line tools such as NSLOOKUP or DIG. You can also useonline web services that allow you toperform quick searches and display the information in aconvenient manner.

34. What does "Disable Recursion" in DNS mean?

In the Windows 2000/2003 DNS console (dnsmgmt.msc), under aserver's Properties -> Forwarders tab is the setting Do notuse recursion for this domain. On the Advanced tab you will

find the confusingly similar option Disable recursion (alsodisables forwarders).Recursion refers to the action of a DNS server queryingadditional DNS servers (e.g. local ISP DNS or the root DNSservers) to resolve queries that it cannotresolve from its own database

35. What could cause the Forwarders and Root Hints to begrayed out?

Win2K configured your DNS server as a private root server

36. What is a "Single Label domain name" and what sort of

issues can it cause?Single-label names consist of a single word like "contoso".• Single-label DNS names cannot be registered by using an



Internet registrar.• Client computers and domain controllers that joined to single-label domains require additional configuration todynamically register DNS records insingle-label DNS zones. • Client computers and domain controllers may require additional configuration to resolveDNS queries in single-label DNS zones.• By default, Windows Server 2003-based domain members,Windows XP-based domain members, and Windows 2000-baseddomain members do not perform dynamicupdates to single-label DNS zones.• Some server-based applications are incompatible withsingle-label domain names. Application support may not existin the initial release of an application,or support may be dropped in a future release. For example,Microsoft Exchange Server 2007 is not supported inenvironments in which single-label DNS isused.• Some server-based applications are incompatible with thedomain rename feature that is supported in Windows Server2003 domain controllers and in WindowsServer 2008 domain controllers. These incompatibilitieseither block or complicate the use of the domain renamefeature when you try to rename a single-labelDNS name to a fully qualified domain name.

37. What is the "in-addr.arpa" zone used for?

When creating DNS records for your hosts, A records makesense. After all, how can the world find your mail serverunless the IP address of that server is associated with itshostname within a DNS database? However, PTR records aren'tas easily understood. If you already have a zone file, whydoes there have to be a separate in-addr.arpa zonecontaining PTR records matching your A records? And whoshould be making those PTR records--you or your provider?Let's start by defining in-addr.arpa. .arpa is actually aTLD like .com or .org. The name of the TLD comes fromAddress and Routing Parameter Area and it has beendesignated by the IANA to be used exclusively for Internetinfrastructure purposes. In other words, it is an importantzone and an integral part of the inner workings of DNS. The

RFC for DNS (RFC 1035) has an entire section on thein-addr.arpa domain. The first two paragraphs in thatsection state the purpose of the domain: "The Internet usesa special domain to support gateway location and Internetaddress to host mapping. Other classes may employ a similarstrategy in other domains. The intent of this domain is toprovide a guaranteed method to perform host address to hostname mapping, and to facilitate queries to locate allgateways on a particular network in the Internet. Note thatboth of these services are similar to functions that couldbe performed by inverse queries; the difference is that thispart of the domain name space is structured according to

address, and hence can guarantee that the appropriate datacan be located without an exhaustive search of the domainspace." In other words, this zone provides a database of all



allocated networks and the DNS reachable hosts within thosenetworks. If your assigned network does not appear in thiszone, it appears to be unallocated. And if your hosts don'thave a PTR record in this database, they appear to beunreachable through DNS. Assuming an A record exists for ahost, a missing PTR record may or may not impact on the DNSreachability of that host, depending upon the applicationsrunning on that host. For example, a mail server willdefinitely be impacted as PTR records are used in mailheader checks and by most anti-SPAM mechanisms. Dependingupon your web server configuration, it may also depend uponan existing PTR record. This is why the DNS RFCs recommendthat every A record has an associated PTR record. But whoshould make and host those PTR records? Twenty years agowhen you could buy a full Class C network address (i.e. 254host addresses) the answer was easy: you. Remember, thein-addr.arpa zone is concerned with delegated networkaddresses. In other words, the owner of the network addressis authoritative (i.e. responsible) for the host PTR recordsassociated with that network address space. If you only ownone or two host addresses within a network address space,the provider you purchased those addresses from needs tohost your PTR records as the provider is the owner of (i.e.authoritative for) the network address. Things are a bitmore interesting if you have been delegated a CIDR block ofaddresses. The in-addr.arpa zone assumes a classfuladdressing scheme where a Class A address is one octet (or/8), a Class B is 2 octets (or /16) and a Class C is 3octets (or /24). CIDR allows for delegating address spaceoutside of these boundaries--say a /19 or a /28. RFC 2317provides a best current practice for maintainingin-addr.arpa with these types of network allocations. Hereis a summary regarding PTR records: • Don't wait until userscomplain about DNS unreachability--be proactive and ensurethere is an associated PTR record for every A record. • If your provider hosts your A records, they should also hostyour PTR records. • If you only have one or two assigned IP addresses, your provider should host your PTR records asthey are authoritative for the network those hosts belongto. • If you own an entire network address (e.g. a Class C address ending in 0), you are responsible for hosting yourPTR records. • If you are configur

ing an internal DNS serverwithin the private address ranges (e.g. 10.0.0.0 or192.168.0.0), you are responsible for your own internal PTRrecords. • Remember: the key to PTR hosting is knowing who is authoritative for the network address for your domain.When in doubt, it probably is not you.

38. What are the requirements from DNS to support AD?

When you install Active Directory on a member server, themember server is promoted to a domain controller. ActiveDirectory uses DNS as the locationmechanism for domain controllers, enabling computers on the

network to obtain IP addresses of domain controllers.During the installation of Active Directory, the service(SRV) and address (A) resource records are dynamically



registered in DNS, which are necessary forthe successful functionality of the domain controllerlocator (Locator) mechanism.To find domain controllers in a domain or forest, a clientqueries DNS for the SRV and A DNS resource records of thedomain controller, which provide theclient with the names and IP addresses of the domaincontrollers. In this context, the SRV and A resource recordsare referred to as Locator DNS resourcerecords.When adding a domain controller to a forest, you areupdating a DNS zone hosted on a DNS server with the LocatorDNS resource records and identifying thedomain controller. For this reason, the DNS zone must allowdynamic updates (RFC 2136) and the DNS server hosting thatzone must support the SRV resourcerecords (RFC 2782) to advertise the Active Directorydirectory service. For more information about RFCs, see DNSRFCs.If the DNS server hosting the authoritative DNS zone is nota server running Windows 2000 or Windows Server 2003,contact your DNS administrator todetermine if the DNS server supports the required standards.If the server does not support the required standards, orthe authoritative DNS zone cannot beconfigured to allow dynamic updates, then modification isrequired to your existing DNS infrastructure.

39. How do you manually create SRV records in DNS?

this is on windows server

go to run ---> dnsmgmt.msc

rightclick on the zone you want to add srv record to andchoose "other new record"

and choose service location(srv).....

40. Name 3 benefits of using AD-integrated zones.

1. you can give easy name resolution to ur clients.

2. By creating AD- integrated zone you can also trace hackerand spammer by creating reverse zone.

3. AD integrated zoned all for incremental zone transferswhich on transfer changes and not the entire zone. Thisreduces zone transfer traffic.

4. AD Integrated zones suport both secure and dmanic updates.

5. AD integrated zones are stored as part of the activedirectory and support domain-wide or forest-wide replicationthrough application pertitions in AD.

41. What are the benefits of using Windows 2003 DNS whenusing AD-integrated zones?



Advantages:

DNS supports Dynamic registration of SRV records registeredby a Active Directory server or a domain controller duringpromotion. With the help of SRV records client machines canfind domain controllers in the network.

1. DNS supports Secure Dynamic updates. Unauthorized accessis denied.

2. Exchange server needs internal DNS or AD DNS to locateGlobal Catalog servers.

3. Active Directory Integrated Zone. If you have more thanone domain controller (recommended) you need not worry aboutzone replication. Active Directory replication will takecare of DNS zone replication also.

4. If your network use DHCP with Active Directory then noother DHCP will be able to service client requests comingfrom different network. It is because DHCP server isauthorized in AD and will be the only server to participateon network to provide IP Address information to client machines.

5. Moreover, you can use NT4 DNS with Service Pack 4 orlater. It supports both SRV record registration and DynamicUpdates.

Using Microsoft DNS gives the following benefits:If you implement networks that require secure updates.If you want to take benefit of Active Directory replication.If you want to integrate DHCP with DNS for Low-level clientsto register their Host records in Zone database.

42. You installed a new AD domain and the new (and first) DC

has not registered its SRV records in DNS. Name a fewpossible causes.

The machine cannot be configured with DNS client her ownThe DNS service cannot be run

43. What are the benefits and scenarios of using Stub zones?

One of the new features introduced in the Windows Server2003-based implementation of DNS are stub zones. Its mainpurpose is to provide name resolution in domains, for whicha local DNS server is not authoritative. The stub zonecontains only a few records: - Start of Authority (SOA)record pointing to a remote DNS server that is considered tobe the best source of information about the target DNSdomain, - one or more Name Server (NS) records (including

the entry associated with the SOA record), which areauthoritative for the DNS domain represented by the stubzone, - corresponding A records for each of the NS entries



(providing IP addresses of the servers). While you can alsoprovide name resolution for a remote domain by eithercreating a secondary zone (which was a common approach inWindows Server 2000 DNS implementation) or delegation (whendealing with a contiguous namespace), such approach forcesperiodic zone transfers, which are not needed when stubzones are used. Necessity to traverse network in order toobtain individual records hosted on the remote Name Serversis mitigated to some extent by caching process, which keepsthem on the local server for the duration of theirTime-to-Live (TTL) parameter. In addition, records residingin a stub zone are periodically validated and refreshed inorder to avoid lame delegations.

44. What are the benefits and scenarios of using ConditionalForwarding?Conditional forwarding is a new feature of DNS in Windows Server2003 that can be used to speed up name resolution in certainscenarios. They can also be used to help companies resolve eachother's namespace in a situation where companies collaborate amerger is underway. This article will look in detail at howconditional forwarding works, how to configure it, and when youmight use it. But first, let's briefly review the concepts offorwarding and forwarders in traditional DNS, starting withdifferent types of name queries.

45. What are the differences between Windows Clustering, Network Load Balancing and Round Robin, and scenarios foreach use?

I will make a few assumptions here: 1) By "WindowsClustering Network Load Balancing" you mean Windows NetworkLoad Balancing software included in Windows Server softwarea.k.a NLB., and 2) By Round Robin, you mean DNS Round Robinmeaning the absence of a software or hardware load balancingdevice, or the concept of the Round Robin algorithmavailable in just about every load balancing solution.

Microsoft NLB is designed for a small number (4 - 6) ofWindows Servers and a low to moderate number of newconnections per second, to provide distribution of webserver requests to multiple servers in a virtual resource

pool. Some would call this a "cluster", but there are suttledifferences between a clustered group of devices and a moreloosely configured virtual pool. From the standpoint ofscalability and performance, almost all hardware loadbalancing solutions are superior to this and other lessknown software load balancing solutions [e.g. Bright Tigercirca 1998].

DNS Round Robin is an inherent load balancing method builtinto DNS. When you resolve an IP address that has more thanone A record, DNS hands out different resolutions todifferent requesting local DNS servers. Although there are

several factors effecting the exact resulting algorithm(e.g. DNS caching, TTL, multiple DNS servers [authoritativeor cached]), I stress the term "roughly" when I say it



roughly results in an even distribution of resolutions toeach of the addresses specified for a particular URL. Itdoes not however, consider availability, performance, or anyother metric and is completely static. The basic RRalgorithm is available in many software and hardware loadbalancing solutions and simply hands the next request to thenext resource and starts back at the first resource when ithits the last one.

NLB is based on proprietary software, meant for small groupsof Windows servers only on private networks, and is dynamicin nature (takes into account availability of a server, andin some cases performance). "Round Robin", DNS or otherwise,is more generic, static in nature (does not take intoaccount anything but the resource is a member of theresource pool and each member is equal), and ranges from DNSto the default static load balancing method on everyhardware device in the market.

46. How do I work with the Host name cache on a client computer?

A host name is an alias assigned to identify a TCP/IP host or itsinterfaces. Host names are used in all TCP/IP environments. Thefollowing describes the attributes of a host name:

The host name does not have to match the NetBIOS computername, and a host name can contain as many as 255 characters.

Multiple host names can be assigned to the same host.

Host names are easier to remember than IP addresses.

A user can specify host name instead of an IP address whenusing Windows Sockets applications, such as the Ping tool orInternet Explorer.

A host name should correspond to an IP address mapping that isstored either in the local Hosts file or in a database on aDNS server. TCP/IP for Windows XP and Windows Server 2003 alsouse NetBIOS name resolution methods for host names.

The Hostname tool displays the computer name of your Windows–based computer, as configured from the Computer Name tab ofthe System item of Control Panel.

47. How do I clear the DNS cache on the DNS server?To clear the server names cache

* Using the Windows interface

* Using a command line

Using the Windows interface

1. Open DNS.

2. In the console tree, click the applicable DNS server.

Where?



* DNS/applicable DNS server

3. On the Action menu, click Clear Cache.

Notes

* To perform this procedure, you must be a member of theAdministrators group on the local computer, or you must havebeen delegated the appropriate authority. If the computer isjoined to a domain, members of the Domain Admins group mightbe able to perform this procedure. As a security bestpractice, consider using Run as to perform this procedure.

* To open DNS, click Start, click Control Panel,double-click Administrative Tools, and then double-click DNS.

Using a command line

1. Open Command Prompt.

2. Type the following command and then press ENTER:

Dnscmd ServerName /clearcache

48. What is the 224.0.1.24 address used for?

WINS server group address. Used to support autodiscovery anddynamic configuration of replication for WINS servers. Formore information, see WINS replication overview

WINS server group address. Used to support autodiscovery anddynamic configuration of replication for WINS servers.

49. What is WINS and when do we use it?In the Windows Server family, the primary means for clientcomputer to locate and communicate with other computers onan Internet Protocol (IP) network is by using Domain NameSystem (DNS). However, clients that use older versions ofWindows, such as Windows NT 4.0, use network basic I/Osystem (NetBIOS) names for network communication. Some

applications that run on Windows Server 2003 may also useNetBIOS names for network communication. Using NetBIOS namesrequires a method of resolving NetBIOS names to IP .Using a WINS server is essential for any Windows clientcomputer to work with other Windows computers over theInternet. In addition, using a WINS server is essential forany Windows client computer at Indiana University thatintends to use Microsoft network resources. To use WINSservices, you must insert into your TCP/IP networkingconfiguration the IP address of the WINS servers you wish touse.

50. Can you have a Microsoft-based network without any WINSserver on it? What are the "considerations" regarding notusing WINS?



Yes, you can. WINS was designed to speed up information flow aboutthe Windows workstations in a network. It will work without it, andmost networks do not utilize WINS servers anymore because it isbased on an old protocol (NetBUI) which is no longer in common use.

51. Describe the differences between WINS push and pull

replications.

To replicate database entries between a pair of WINSservers, you must configure each WINS server as a pullpartner, a push partner, or both with the other WINS server.

* A push partner is a WINS server that sends a messageto its pull partners, notifying them that it has new WINSdatabase entries. When a WINS server's pull partner respondsto the message with a replication request, the WINS serversends (pushes) copies of its new WINS database entries (alsoknown as replicas) to the requesting pull partner.

* A pull partner is a WINS server that pulls WINSdatabase entries from its push partners by requesting anynew WINS database entries that the push partners have. Thepull partner requests the new WINS database entries thathave a higher version number than the last entry the pullpartner received during the most recent replication.

52. What is the difference between tombstoning a WINS record and simply deleting it?

Simple deletion removes the records that are selected in theWINS console only from the local WINS server you arecurrently managing. If the WINS records deleted in this wayexist in WINS data replicated to other WINS servers on yournetwork, these additional records are not fully removed.Also, records that are simply deleted on only one server canreappear after replication between the WINS server wheresimple deletion was used and any of its replication partners.Tombstoning marks the selected records as tombstoned, thatis, marked locally as extinct and immediately released fromactive use by the local WINS server. This method allows thetombstoned records to remain present in the server database

for purposes of subsequent replication of these records toother servers. When the tombstoned records are replicated,the tombstone status is updated and applied by other WINSservers that store replicated copies of these records. Eachreplicating WINS server then updates and tombstones

53. Name the NetBIOS names you might expect from a Windows 2003 DCthat is registered in WINS. If a Microsoft Windows NT 3.5-based client computer does not receivea response from the primary Windows Internet Name Service (WINS)server, it queries the secondary WINS server to resolve a NetBIOSname. However, if a NetBIOS name is not found in the primary WINS

server's database, a Windows NT 3.5-based client does not query thesecondary WINS server.



In Microsoft Windows NT 3.51 and later versions of the Windowsoperating system, a Windows-based client does query the secondaryWINS server if a NetBIOS name is not found in the primary WINSserver's database. Clients that are running the following versionsIn Windows NT 3.51, Windows NT 4, Windows 95, Windows 98, Windows2000, Windows Millennium Edition, Windows XP, and Windows Server2003, you can specify up to 12 WINS servers. Additional WINS serversare useful when a requested name is not found in the primary WINSserver's database or in the secondary WINS server's database. Inthis situation, the WINS client sends a request to the next serverin the list.

54. Describe the role of the routing table on a host and ona router.

During the process of routing, decisions of hosts androuters are aided by a database of routes known as therouting table. The routing table is not exclusive to arouter. Depending on the routable protocol, hosts may alsohave a routing table that may be used to decide the bestrouter for the packet to be forwarded. Host-based routingtables are optional for the Internet Protocol, as well asobsolete routable protocols such as IPX.

55. What are routing protocols? Why do we need them? Name a few.

A routing protocol is a protocol that specifies how routerscommunicate with each other, disseminating information thatenables them to select routes between any two nodes on acomputer network, the choice of the route being done byrouting algorithms. Each router has a prior knowledge onlyof networks attached to it directly. A routing protocolshares this information first among immediate neighbors, andthen throughout the network. This way, routers gainknowledge of the topology of the network. For a discussionof the concepts behind routing protocols, see: Routing.

The term routing protocol may refer specifically to oneoperating at layer three of the OSI model, which similarlydisseminates topology information between routers.

Many routing protocols used in the public Internet aredefined in documents called RFCs.[1][2][3][4]

Although there are many types of routing protocols, twomajor classes are in widespread use in the Internet:link-state routing protocols, such as OSPF and IS-IS; andpath vector or distance vector protocols, such as BGP, RIPand EIGRP.

56. What are router interfaces? What types can they be?

Routers can have many different types of connectors; fromEthernet, Fast Ethernet, and Token Ring to Serial and ISDNports. Some of the available configurable items are logical



addresses (IP,IPX), media types, bandwidth, andadministrative commands. Interfaces are configured ininterface mode which you get to from global configurationmode after logging in.The media type is Ethernet, FastEthernet, GigabitEthernet,Serial, Token-ring, or other media types. You must keep inmind that a 10Mb Ethernet interface is the only kind ofEthernet interface called Ethernet. A 100Mb Ethernetinterface is called a FastEthernet interface and a 1000MbEthernet interface is called a GigabitEthernet interface.

57. In Windows 2003 routing, what are the interface filters?

NAT actsas a middle man between the internal and external network;packets coming from the private network are handled by NAT and thentransferred to their intended destination. A single external addressis used on the Internet so that the internal IP addresses are not

shown. A table is created on the router that lists local and globaladdresses and uses it as a reference when translating IP addresses.

NAT can work in several ways:Static NATAn unregistered IP address is mapped to a registered IP address on aone-to-one basis - which is useful when a device needs to beaccessed from outside the network.

Dynamic NATAn unregistered IP address is mapped to a registered IP address froma group of registered IP addresses. For example, a computer

192.168.10.121 will translate to the first available IP in a rangefrom 212.156.98.100 to 212.156.98.150.

OverloadingA form of dynamic NAT, it maps multiple unregistered IP addresses toa single registered IP address, but in this case uses differentports. For example, IP address 192.168.10.121 will be mapped to212.56.128.122:port_number (212.56.128.122:1080).

OverlappingThis when addresses in the inside network overlap with addresses inthe outside network - the IP addresses are registered on another

network too. The router must maintain a lookup table of theseaddresses so that it can intercept them and replace them withregistered unique IP addresses.

How NAT worksA table of information about each packet that passes through ismaintained by NAT.

When a computer on the network attempts to connect to a website onthe Internet:the header of the source IP address is changed and replaced with theIP address of the NAT computer on the way out the "destination" IP

address is changed (based on the records in the table) back to thespecific internal private class IP address in order to reach the



computer on the local network on the way back in Network AddressTranslation can be used as a basic firewall – the administrator isable to filter out packets to/from certain IP addresses andallow/disallow access to specified ports. It is also a means ofsaving IP addresses by having one IP address represent a group ofcomputers.

Setting up NATTo setup NAT you must start by opening the Configure your serverwizard in administrative tools and selecting the RRAS/VPN Serverrole. Now press next and the RRAS setup wizard will open. The screenbelow shows the Internet Connection screen in which you must specifywhich type of connection to the Internet and whether or not you wantthe basic firewall feature to be enabled.

Press next to continue. The installation process will commence andservices will be restarted, after which the finish screen will bedisplayed - showing what actions have taken place.

Configuring NATConfiguration of NAT takes place from the Routing and Remote Accessmmc found in the Administrative Tools folder in the Control Panel oron the start menu.

The screenshot below shows the routing and remote access mmc.Select which interface you wish to configure and double click it.This will bring up the properties window giving you the option tochange settings such as packet filtering and port blocking, as wellas enabling/disabling certain features, such as the firewall. Theremote router (set up previously) properties box is shown below. TheNAT/Basic Firewall tab is selected.

You are able to select the interface type– to specify what the network connection will be. In my example Ihave selected for the interface to be a public interface connectedto the internet. NAT and the basic firewall option have also beenenabled. The inbound and outbound buttons will open a window thatwill allow you restrict traffic based on IP address or protocolpacket attributes. As per your instructions, certain TCP packetswill be dropped before they reach the client computer. Thus, makingthe network safer and giving you more functionality. This is useful

if, for example, you wanted to reject all packets coming from ablacklisted IP address or restrict internal users access to port 21(ftp).

For further firewall configuration, go to the Services and Portstab. Here you can select which services you would like to provideyour users access to. You can also add more services by specifyingdetails such as the incoming and outgoing port number.

The list of services shown in the above screenshot are preset. PressAdd to bring up the window that will allow the creation of a newservice or select an available service and press Edit to modify that

service. You will be asked to specify the name, TCP and UDP portnumber and the IP address of the computer hosting that service.



If the services in the list aren’t enabled then any client computer

on the Windows 2003 domain will not be able to access that specificservice. For example, if the computer was configured as shown in theimage above and a client computer tried to connect to an ftp site,he would be refused access. This section can prove to be very usefulfor any sized networks, but especially small ones.

That concludes this article. As you have seen, Network AddressTranslation is a useful feature that adds diversity and security toa network in a small to medium sized company. With the advent,

58. What is NAT?

Windows Server 2003 provides network address translation(NAT) functionality as a part of the Routing and RemoteAccess service. NAT enables computers on small- tomedium-sized organizations with private networks to access

resources on the Internet or other public network. Thecomputers on a private network are configured with reusableprivate Internet Protocol version 4 (IPv4) addresses; thecomputers on a public network are configured with globallyunique IPv4 (or, rarely at present, Internet Protocolversion 6 [IPv6]) addresses. A typical deployment is a smalloffice or home office (SOHO), or a medium-sized business,that uses Routing and Remote Access NAT technology to enablecomputers on the internal corporate network to connect toresources on the Internet without having to deploy a proxyserver.

59. What is the real difference between NAT and PAT?Take NAT (Network Address Translation) and PAT (Port AddressTranslation). NAT allows you to translate or map one IPaddress onto another single ip address. PAT on the otherhand is what is most commonly referred to as NAT. In a PATsystem you have a single or group of public IP addressesthat are translated to multiple internal ip addresses bymapping the TCP/UDP ports to different ports. This meansthat by using some "magic" on a router or server you can getaround problems that you might have with two web browserssending a request out the same port.

60. How do you configure NAT on Windows 2003?http://www.windowsnetworking.com/articles_tutorials/NAT_Windows_2003_Setup_Configuration.htmlConfigure Routing and Remote AccessTo activate Routing and Remote Access, follow these steps:

1. Click Start, point to All Programs, point toAdministrative Tools, and then click Routing and Remote Access.

2. Right-click your server, and then click Configure andEnable Routing and Remote Access.

3. In the Routing and Remote Access Setup Wizard, clickNext, click Network address translation (NAT), and then

click Next.4. Click Use this public interface to connect to the



Internet, and then click the network adapter that isconnected to the Internet. At this stage you have the optionto reduce the risk of unauthorized access to your network.To do so, click to select the Enable security on theselected interface by setting up Basic Firewall check box.

5. Examine the selected options in the Summary box, andthen click Finish.

Configure dynamic IP address assignment for private networkclientsYou can configure your Network Address Translation computerto act as a Dynamic Host Configuration Protocol (DHCP)server for computers on your internal network. To do so,follow these steps:

1. Click Start, point to All Programs, point toAdministrative Tools, and then click Routing and Remote Access.

2. Expand your server node, and then expand IP Routing.3. Right-click NAT/Basic Firewall, and then click Properties.4. In the NAT/Basic Firewall Properties dialog box, click

the Address Assignment tab.5. Click to select the Automatically assign IP addresses

by using the DHCP allocator check box. Notice that defaultprivate network 192.168.0.0 with the subnet mask of255.255.0.0 is automatically added in the IP address and theMask boxes. You can keep the default values, or you canmodify these values to suit your network.

6. If your internal network requires static IP assignmentfor some computers -- such as for domain controllers or forDNS servers -- exclude those IP addresses from the DHCPpool. To do this, follow these steps:

1. Click Exclude.2. In the Exclude Reserved Addresses dialog box,

click Add, type the IP address, and then click OK.3. Repeat step b for all addresses that you want to

exclude.4. Click OK.

Configure name resolutionTo configure name resolution, follow these steps:

1. Click Start, point to All Programs, point toAdministrative Tools, and then click Routing and Remote Access.2. Right-click NAT/Basic Firewall, and then click Properties.3. In the NAT/Basic Firewall Properties dialog box, click

the Name Resolution tab.4. Click to select the Clients using Domain Name System

(DNS) check box. If you use a demand-dial interface toconnect to an external DNS server, click to select theConnect to the public network when a name needs to beresolved check box, and then click the appropriate dial-upinterface in the list.

61. How do you allow inbound traffic for specific hosts on Windows2003 NAT?



You can use the Windows Server 2003 implementation of IPSecto compensate for the limited protections provided byapplications for network traffic, or as a network-layerfoundation of a defense-in-depth strategy. Do not use IPSecas a replacement for other user and application securitycontrols, because it cannot protect against attacks fromwithin established and trusted communication paths. Yourauthentication strategy must be well defined and implementedfor the potential security provided by IPSec to be realized,because authentication verifies the identity and trust ofthe computer at the other end of the connection.

62. What is VPN? What types of VPN does Windows 2000 and beyond work with natively?

L2TP (layer 2 tunneling protocol )

vpn server is also know as L2TP server in native mode & inPPTP in mixed mode

PN gives extremely secure connections between privatenetworks linked through the Internet. It allows remotecomputers to act as though they were on the same secure,local network.

63. What is IAS? In what scenarios do we use it?

IAS is called as Internet Authentication Service. It's usedby for configuring centralised authentication using RADIUSserver.

64. What's the difference between Mixed mode and Native mode in AD when dealing with RRAS?

When you are in Mixed mode certain options in the dial-intab of the user proeprties are disabled. And some of theRRAS policies are also disabled. So if you want high levelsecurity with all the advanced feature then change the AD toNative mode.

65. What is the "RAS and IAS" group in AD?

Used for managing security and allowing administration forthe respective roles of the server.

66. What are Conditions and Profile in RRAS Policies?

The conditions and profiles are used to set somerestrictions based on the media type, connection method,group membership and lot more. So if used matches thoseconditions mentioned in the profile then he can allowed /denied access to RAS / VPN server.

67. What types or authentication can a Windows 2003 based RRAS work with?

It supports authentication methods like MSCHAPv2, MSCHAP,SPAP, EAP, Digest authentication. ( You can check it bygoing to properties of your server in RRAS )

68. How does SSL work?



Internet communication typically runs through multipleprogram layers on a server before getting to the requesteddata such as a web page or cgi scripts.

The outer layer is the first to be hit by the request. Thisis the high level protocols such as HTTP (web server), IMAP(mail server), and FTP (file transfer).

Determining which outer layer protocol will handle therequest depends on the type of request made by the client.This high level protocol then processes the request throughthe Secure Sockets Layer. If the request is for a non-secureconnection it passes through to the TCP/IP layer and theserver application or data.

If the client requested a secure connection the ssl layerinitiates a handshake to begin the secure communicationprocess. Depending on the SSL setup on the server, it mayrequire that a secure connection be made before allowingcommunication to pass through to the TCP/IP layer in whichcase a non-secure request will send back an error asking forthem to retry securely (or simply deny the non-secureconnection).

69. How does IPSec work?

IPSec is an Internet Engineering Task Force (IETF) standardsuite of protocols that provides data authentication,integrity, and confidentiality as data is transferredbetween communication points across IP networks. IPSecprovides data security at the IP packet level. A packet is adata bundle that is organized for transmission across anetwork, and it includes a header and payload (the data inthe packet). IPSec emerged as a viable network securitystandard because enterprises wanted to ensure that datacould be securely transmitted over the Internet. IPSecprotects against possible security exposures by protectingdata while in transit.

70. How do I deploy IPSec for a large number of computers?

Just use this program Server and Domain Isolation UsingIPsec and Group Policy

71. What types of authentication can IPSec use?

Deploying L2TP/IPSec-based Remote Access

Deploying L2TP-based remote access VPN connections usingWindows Server 2003 consists of the following:

* Deploy certificate infrastructure

* Deploy Internet infrastructure

* Deploy AAA infrastructure

* Deploy VPN servers



* Deploy intranet infrastructure

* Deploy VPN clients

Implantando L2TP/IPSec-based Acesso RemotoImplantando L2TP com base em conexões VPN de acesso remotousando o Windows Server 2003 é constituída pelos seguinteselementos:

* Implantar certificado infra-estrutura* Implantar infra-estrutura Internet* Implantar infra-estrutura AAA* Implementar VPN servidores* Implantar intranet infra-estrutura* Implementar clientes VPN

72. What is PFS (Perfect Forward Secrecy) in IPSec?

In an authenticated key-agreement protocol that uses publickey cryptography, perfect forward secrecy (or PFS) is theproperty that ensures that a session key derived from a setof long-term public and private keys will not be compromisedif one of the (long-term) private keys is compromised in thefuture.Forward secrecy has been used as a synonym for perfectforward secrecy [1], since the term perfect has beencontroversial in this context. However, at least onereference [2] distinguishes perfect forward secrecy fromforward secrecy with the additional property that an agreedkey will not be compromised even if agreed keys derived fromthe same long-term keying material in a subsequent run arecompromised.

73. How do I monitor IPSec?

To test the IPSec policies, use IPSec Monitor. IPSec Monitor(Ipsecmon.exe) provides information about which IPSec policyis active and whether a secure channel between computers isestablished.

74. Looking at IPSec-encrypted traffic with a sniffer. What packettypes do I see?

You can see the packages to pass, but you can not see itscontents

IPSec Packet TypesIPSec packet types include the authentication header (AH)for data integrity and the encapsulating security payload(ESP) for data confidentiality and integrity.The authentication header (AH) protocol creates an envelopethat provides integrity, data origin identification andprotection against replay attacks. It authenticates every

packet as a defense against session-stealing attacks.Although the IP header itself is outside the AH header, AHalso provides limited verification of it by not allowing



changes to the IP header after packet creation (note thatthis usually precludes the use of AH in NAT environments,which modify packet headers at the point of NAT). AH packetsuse IP protocol 51.The encapsulating security payload (ESP) protocol providesthe features of AH (except for IP header authentication),plus encryption. It can also be used in a null encryptionmode that provides the AH protection against replay attacksand other such attacks, without encryption or IP headerauthentication. This can allow for achieving some of thebenefits of IPSec in a NAT environment that would notordinarily work well with IPSec. ESP packets use IP protocol 50.

75. What can you do with NETSH?

Netsh is a command-line scripting utility that allows youto, either locally or remotely, display, modify or scriptthe network configuration of a computer that is currentlyrunning.

76. How do I look at the open ports on my machine?

Windows: Open a command prompt (Start button -> Run-> type"cmd"), and type:netstat -a

Linux: Open an SSH session and type:netstat -an

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