Ccna 2

Network engineer interview questions

1. What is a default gateway? - The exit-point from one network and entry-way into

another network, often the router of the network.

2. How do you set a default route on an IOS Cisco router? - ip route 0.0.0.0 0.0.0.0

x.x.x.x [where x.x.x.x represents the destination address]

3. What is the difference between a domain local group and a global group? -

Domain local groups grant permissions to objects within the domain in which the

reside. Global groups contain grant permissions tree or forest wide for any objects

within the Active Directory.

4. What is LDAP used for? - LDAP is a set of protocol used for providing access to

information directories.

5. What tool have you used to create and analyze packet captures? - Network

Monitor in Win2K / Win2K3, Ethereal in Linux, OptiView Series II (by Fluke

Networks).

6. How does HSRP work?

7. What is the significance of the IP address 255.255.255.255? - The limited

broadcast address is utilized when an IP node must perform a one-to-everyone

delivery on the local network but the network ID is unknown.

1. User(s) are complaining of delays when using the network. What would you do?

2. What are some of the problems associated with operating a switched LAN?

3. Name some of the ways of combining TCP/IP traffic and SNA traffic over the same

link.

4. What sort of cabling is suitable for Fast Ethernet protocols?

5. What is a Class D IP address?

6. Why do I sometimes lose a server’s address when using more than one server?

7. What is Firewall?

8. How do I monitor the activity of sockets?

9. How would I put my socket in non-blocking mode?

10. What are RAW sockets?

11. What is the role of TCP protocol and IP protocol.

12. What is UDP?

13. How can I make my server a daemon?

14. How should I choose a port number for my server?

15. Layers in TCP/IP

16. How can I be sure that a UDP message is received?

17. How to get IP header of a UDP message

18. Writing UDP/SOCK_DGRAM applications

19. How many bytes in an IPX network address?

20. What is the difference between MUTEX and Semaphore?

21. What is priority inversion?

22. Different Solutions to dining philosophers problem.

23. What is a message queue?

24. Questions on Shared Memory.

25. What is DHCP?

26. Working of ping, telnet, gopher.

27. Can I connect two computers to internet using same line ?

1. Workers can not print from the printer, there user log on are correct and are allowed

to print from that printer in active directory. How would you resolve this issue?

2. What is the difference between hub and switch?

3. Your hard drive is partitioned as follows: 8 gigs for OS drive C, 8 gigs for Hot

Swappable dirve D and rest is free as dirve E. Your drive C crashes, how would you

reboot your system without installing a new operating system?

4. Your computer gives you “non-disk error” before you log on what would you do to

make your computer work?

1. Workers can not print from the printer, there user logon are correct and are allowed to

print from that printer in active directory. How would you resolve this issue?

This is vague and could have multiple responses. Here are a few.

1. Verify printer is set as default.

2. Verify users have local privileges set properly to print.

3. Is print server delivering correct drivers?

4. Is local naming convention for printer correct?

5. If pre Win2000 workstation, naming convention must be less than 12 characters.

6. Make sure no viruses present. Some Viruses can shut down IPC shares and printing

services.

2. What is the difference between hub and switch?

A hub is not smart and allows all connected nodes/networks to communicate with each other.

You a are limited to 10/100Mb half duplex operation on a hub. To hook two hubs togethor you

would use a crossover cable. Most hubs also have a crossover port which will allow you to use

a regular cable to hook two hubs/switches togethor.

A switch on the other hand can be an OSI Model layer 2 or 3 device. A switch forwards

information by mac address. The mack address is a hard coded alpha numeric number that is

used to identify a network adapter. Whenever a call is made to another computer, the switch

looks in it’s mac address table and see’s if this node is directly connected to the switch by

looking it up in the mac address database. If it is not, however, if forwards it down all switch

ports looking for the destination. A layer 2 switch is even smarter. It can actually route traffic

based on it’s layer 3 address. It will look up the destination in it’s mac address table first, if

does not find it, it will forward it by looking at the route table and send it on it’s merry way to

it’s destination. A switch will also allow you to set a switch port at 10/100Mb full duplex to

increase node communication speed.

Hubs should be used in smaller networking environments and switches should be used

whenever you need to segment your network or you are having problems with collisions on

your ethernet network. If you have over a 100 clients in a location, it’s a good idea to uses

switches.

If you intend on using them both, you would normally use the switch as the backbone and the

hubs as connections. Each hub would have it’s own switch port on the switch. I normally

reccommend that if your going to use a switch in place of a hub then get rid of all your hubs

and move completely to switches. This will allow for increased network performance, a more

structured segmenting of the network, and better traffic control. Hubs, since they are not

smart, send broadcasts down all ports unlike a switch, which can cause performance

degradation on the network. This causes all clients/nodes to have to respond to the broadcast.

3. Your hard drive is partitioned as follows: 8 gigs for OS drive C, 8 gigs for Hot Swappable

drive D and rest is free as drive E. Your drive C crashes, how would you reboot your system

without installing a new operating system?

This is also vague and poorly put together. It is represented as a single HDD but the

reference to Hot Swappable would infer a secondary device. Perhaps he misunderstands the

technology. As it is unclear, this could have multiple responses as well. Here are a few.

1. It is hard to tell how many physical disks there are based on the description? If it is

hardware related and the first drive has literally crashed physically (head crash for example)

the second drive may have an OS. As it is the only drive referred to as Hot Swappable, you

may be able to remove the drive that crashed and change jumper settings on the second drive

making it the primary drive. Then it will reboot provided it has an OS.

2. If this is a single drive with an NT OS and it is setup with multiple boot partitions, you may

be able to boot to one of the other partitions.

3. You may be able to use the original OS CD or floppy disk and repair the OS installation.

This is provided the HDD is ok and the partition is the only problem.

4. If Hot Swappable means a secondary physical drive, where the first partition is mirrored,

then down the computer and swap the drives. Re-power up.

4. Your computer gives you “non-disk error†before you log on what would you

do to make your computer work?

Again there are potentially multiple scenarios here.

1. Make sure a non OS floppy is not present in A:

2. Make sure hard drive has not crashed.

3. Based on OS, boot from floppy and re-sys disk, or use CD to repair OS.

Security

1. What is a firewall?

2. Describe, genrally, how to manage a firewall

3. What is a Denial of Service attack?

4. What is a “spoofed” packet?

5. What is a SYN Flood?

6. What do you do if you are a victim of a DoS?

7. What is GPG/PGP?

8. What is SSH?

9. What is SSL? How do you create certificates?

10. What would you do if you discovered a UNIX or Network device on your network has

been compromised?

11. What would you do if you discovered a Windows system on your network has been

comrpromised?

12. What is DNS Hijacking?

13. What is a log host?

14. What is IDS or IDP, and can you give me an example of one?

15. Why are proxy servers useful?

16. What is web-caching?

What is a firewall?

Firewall is a device or a software which restricts the unauthorised accesses to and from the

network……….Guys its that simple no need to beat around the bush

A firewall is simply a program or hardware device that filters the information coming through

the Internet connection into your private network or computer system. If an incoming packet

of information is flagged by the filters, it is not allowed through.

Firewalls use one or more of three methods to control traffic flowing in and out of the

network:

* Packet filtering - Packets (small chunks of data) are analyzed against a set of filters. Packets

that make it through the filters are sent to the requesting system and all others are

discarded.

* Proxy service - Information from the Internet is retrieved by the firewall and then sent to

the requesting system and vice versa.

* Stateful inspection - A newer method that doesn’t examine the contents of each packet but

instead compares certain key parts of the packet to a database of trusted information.

Information traveling from inside the firewall to the outside is monitored for specific defining

characteristics, then incoming information is compared to these characteristics. If the

comparison yields a reasonable match, the information is allowed through. Otherwise it is

discarded.

Cisco-specific

1. What is a wildcard mask, and how is it different from a netmask?

2. How do you configure a Cisco switch or router? What are the steps needed?

3. How would I place an interface into trunking mode?

4. How do you shutdown an interface on a router or switch?

5. What is VTP?

6. What is VMPS?

7. What is SPAN/RSPAN?

8. What is flow/netflow?

9. What is TACACS? Radius?

Ans:Where foo equals the interface you’d like to trunk/shutdown.

5. Virtual trunking protocol allows easier management of VLANs over multiple

switches by implementing VTP Server(s) and a VTP domain. When you configure a new

VLAN on one VTP server, the VLAN is distributed through all switches in the domain.

This reduces the need to configure the same VLAN everywhere. There is much more to

VTP, but I assume in an interview you wouldn’t need to get as deep as VTP Pruning,

VTP transparent mode, etc..

9. TACACS+ is a security application used with AAA that provides centralized

validation of users attempting to gain access to a router or network access server.

TACACS+ services are maintained in a database on a TACACS+ daemon running on a

UNIX, Windows NT, or Windows 2000 workstation.

TACACS+ provides for separate and modular authentication, authorization, and

accounting facilities

RADIUS is a distributed client/server system used with AAA that secures networks

against unauthorized access.

AAA means Authentication Authorization Accounting

6. A VLAN Membership Policy Server or “VMPS” is a network switch that contains a

mapping of device information to VLAN.

TACACS+ & RADIUS is protocol, which is used to authentication not a application.

Ans:

1. What is a wildcard mask, and how is it different from a netmask?

> netmask determines the subnet part of the ip address

example

255.255.0.0 class b. the netmask is 255.255

wildcard mask is the opposite. u see this in ospf.

0.0.255.255 .. the 255.255 here defines the host portion. its a wild thing really

2. How do you configure a Cisco switch or router? What are the steps needed?

>enable

#configure terminal

configs are slightly similar

3. How would I place an interface into trunking mode?

en

config t

int s0/0

switchport mode trunk encapsulation dot1q|isl

4. How do you shutdown an interface on a router or switch?

en

config t

int s0/0

shutdown

5. What is VTP?

virtual trunking protocol. set up on switches to manage vlans.

6. What is VMPS?

VLAN membership policy server. maps information regarding vlan

7. What is SPAN/RSPAN?

Switched port analyzer. remote switched port analyzer.

you can monitor traffic flowing to a port from another port.

8. What is flow/netflow?

protocol for collecting IP information

9. What is TACACS? Radius?

terminal access controller access control system

remote access dial in user service

security enabled by aaa

authentication, authorization, accounting

provides a means of validation of users gaining access to a router

accounting not used with radius.

Netmask defines the class. whereas wildcard mask defines the allow or deny which is

used in the access-list. Means, 0.0.0.255 represents… 0=match; 1=ignore; so here in

this wc mask all 0 octets should match exactly where as .255 octet can be anything.

on router or switch to shutdown the interface commands are:

router>enable

router#config t

router(config)#int s0

router(conf_if)# shutdown

this will shut your active interface

The wildcard mask is usually a string of binary digits shown over the subnet number,

telling the router which parts of the subnet number to look at. A binary “0″ over a

particular digit in the subnet number says “Pay attention to this digit.” A “1″ says

“Ignore this digit.” In a wildcard mask, all the binary “0″s in a conventional subnet

mask are replaced by “1″s and all the “1″s are replaced by “0″s.

for trunk mode in switch interface

#int fa 0/1

#switchport trunk allow vlan (vlans you required seperated with coma)

#switchport mode trunk [isl](encapsulation dot1q)

Network administrator interview questions

1. What is the difference between layer 2 and layer 3 in the OSI model?

2. What is the difference between a hub, switch, and router?

3. What is a VLAN?

4. What is the difference between TCP and UDP?

5. How do you distinguish a DNS problem from a network problem?

6. What is a runt, Giant, and collision?

7. What is a broadcast storm?

8. What is the purpose of VRRP?

9. What is a VPN?

10. What information about a peer would I need to establish a VPN?

11. What is a full-class C in CIDR notation?

12. What is a default route?

13. What is a metric?

14. What is a MAC address?

15. What is ARP/RARP?

16. Describe a TCP connection sequence

17. What is MTU?

18. What other TCP setting can you modify besides MTU to shorten packets?

What is the difference between TCP and UDP

TCP is a connection oriented protocol, which means that everytime a packet is sent say from

host A to B, we will get an acknowledgement. Whereas UDP on the other hand, is a

connection less protocol.

Where will it be used : TCP -> Say you have a file transfer and you need to ensure that the file

reaches intact, and time is not a factor, in such a case we can use TCP.

UDP-> Media Streaming, question is say you are watching a movie…would you prefer that

your movie comes..perfectly….but u need to wait a long time before you see the next

frame ?..or would you prefer the movie to keep streaming…Yes…The second option is definely

better….This is when we need UDP

What is a MAC address?

MAC is a machines Physical address, The internet is addressed based on a logical addressing

approach. Say,when the packet reaches say the bridge connection a LAN, the question

is..how does it identify, which computer it needs to send the packet to. For this it uses the

concept of ARP, Address Resolution Protocol, which it uses over time to build up a table

mapping from the Logical addresses to the Physical addresses. Each computer is identified

using its MAC/Physical address ( u can use the ipconfig -all option to get ur MAC address).

What is MTU

The MTU is the “Maximum Transmission Unit” used by the TCP protocol. TCP stands for

Transmission Control Prototcol. The MTU determines the size of packets used by TCP for

each transmission of data. Too large of an MTU size may mean retransmissions if the packet

encounters a router along its route that can’t handle that large a packet. Too small of an MTU

size means relatively more overhead and more acknowledgements that have to be sent and

handled. The MTU is rated in “octets” or groups of 8 bits. The so-called “official” internet

standard MTU is 576, but the standard rating for ethernet is an MTU of 1500.

Ques 2: Diffrence Betw. Switch , Hub, Router..

Hub: 1.it is a layer1 device..used to connect various machine on Lan.2.It forwards broadcast by default.3.It supports one collision domain and one broadcast domain.4.it works on Bus topolog resulting less speed.

Switch: 1. A layer2 device.2. Forward broadcast first time only.3. one broadcast domain & colliosion domains depends on no. of ports.4.It is based on Star Topology giving 100mbps to every pc on Lan.Router: 1. Does not Broadcast by default.2. breaks up Broadcast domain.3. Also called Layer3 switch.

Ques 9: VPN’sVPN(Virtual Private Network )… these are bascially the logical networks on the physical line… you can have many VPN oveer same line..Need of VPN arises when your company need to increase the network but don’t want to buy any more switches.. take an eg. your dept. your room is packed with employees and ur company need to add 4 more persons to ur deptt. what will they do.. the solution is to create VPN’s…you can configure the switch ports in other deptts. and create a specific VLAN of ur deptt.so that the persons can sit there and access to the required pcs.

Ques 12: Default Route…While configuring the Routers we need to give the specific routes if we are configuring a Static route..and for Default..we need not give the single route,, we just have to set the default route command on the router and we set this command on the router of last resort…that is it discovers the near by routes itself..

Ques 15:ARP: Stands for Address Resolution Protocol…whenever a request is sent by a node on one network to the node on another network the Physical address(MAC) is required and for this the IP address need to be flow over the network..whenver a router with that network (IP) gets the msg. the required MAC address is sent through the network this process of converting the IP address to MAC address is Called ARP..and the reverse thats the convertion of the Mac address to the IP address is called RARP ( Reverse Address Resolution Protocol)

What is the difference between layer 2 and layer 3 in the OSI model?

Layer 2 is responsible for switching data whereas Layer 3 is responsible for routing the data.

Layer3: With information gathered from user, Internet protocol make one IP packet with

source IP and Destination IP and other relevant information. It can then route packet through

router to the destination.

Layer2: Soon after it receives IP packet from layer 3, it encapsulate it with frame header

(ATM header in case of ATM technology) and send it out for switching. In case of ethernet it

will send data to MAC address there by it can reach to exact destination.

6)A RUNT is a packet that is too small to traverse the network. Network protocols such as

Ethernet often require that packets be a minimum number of bytes in order to travel the

network. Runts are often the result of packet collisions along a busy network or can result

from faulty hardware that is forming the packets or from corrupted data being sent across the

network.

A giant is a packet that is too large to traverse the network. Network protocols such as

Ethernet often require that packets can not be over a specific number of bytes in order to

travel the network.

3.

VLANs logically segment switched networks based on the functions, project teams, or

applications of the organization regardless of the physical location or connections to the

network.

VLANs provide segmentation based on broadcast domains.

All workstations and servers used by a particular workgroup share the same VLAN,

regardless of the physical connection or location.

VLANs are created to provide segmentation services traditionally provided by physical

routers in LAN configurations.

VLANs address scalability, security, and network management. Routers in VLAN topologies

provide broadcast filtering, security, and traffic flow management.

What is a VPN?

A VPN stands for Virtual Private Network. In english it is a direct tunnel into a remote

network. It allows users to work with certain applications, printers, network drives and

shares as if they where sitting in the office.

How do you distinguish a DNS problem from a network problem?

The first thing to do is to ping any switches, routers, or any other devices on the network. If

your pings come back complete with 0% lost, then it will most likely be a DNS issue. If you

can ping other devices but can not ping the switch that sits in front of the DNS, then it will be

a network issue.

7 Broadcast Storm

A broadcast storm means that your network is overwhelmed with constant broadcast or

multicast traffic. Broadcast storms can eventually lead to a complete loss of network

connectivity as the packets proliferate.

If a certain broadcast transmit threshold is reached, the port drops all broadcast traffic.

Firewalls are one of the best ways to protect your network against broadcast storms.

A state in which a message that has been broadcast across a network results in even more

responses, and each response results in still more responses in a snowball effect. A severe

broadcast storm can block all other network traffic, resulting in a network meltdown.

Broadcast storms can usually be prevented by carefully configuring a network to block illegal

broadcast messages.

What is a metric?

Routing tables contain information used by switching software to select the best route.

Routing algorithms have used many different metrics to determine the best route.

Sophisticated routing algorithms can base route selection on multiple metrics, combining

them in a single (hybrid) metric. All the following metrics have been used:

•Path length

•Reliability

•Delay

•Bandwidth

•Load

•Communication cost

hat is the difference between layer 2 and layer 3 of OSI model?

In the hirarchical design of the osi model , layer 3 is used fot the determinning the path of

packet delivery and method of the packet to deliver. for that the routing and the routed

protocol works .On the layer two , packets are segmented to data enclosed with the mac

address to which the data needs to deliver . on layer 2 , ARP works to resolve the IP address

to mac address .

What is the difference between a hub, switch, and router?

Hub works on layer 1 of OSI model

Swich works on layer 2 of OSI model

Router works on layer 3 of OSI model

Hub does not seperate collision and broadcost domain

swich seperate collision domain but does not seperate broadcost domain.

router does seperate collision and broadcost domain

What is a full-class C in CIDR notation?For class A ..default subnet mask is 255.0.0.0 so CIDR notation is /8For class B ..default subnet mask is 255.255.0.0 so CIDR notation is /16For class C ..default subnet mask is 255.255.255.0 so CIDR notation is /24

Private(Reserved) And Public IP’s?A computer on the Internet is identified by its IP address. In order to avoid address conflicts, IP addresses are publicly registered with the Network Information Centre (NIC). Computers on private TCP/IP LANs however do not need public addresses, since they do not need to be accessed by the public. For this reason, the NIC has reserved certain addresses that will never be registered publicly. These are known as private IP addresses, and are found in the following ranges:From 10.0.0.0 to 10.255.255.255From 172.16.0.0 to 172.31.255.255From 192.168.0.0 to 192.168.255.255

What is Socket?

When a computer program needs to connect to a local or wide area network such as the

Internet, it uses a software component called a socket. The socket opens the network

connection for the program, allowing data to be read and written over the network. It is

important to note that these sockets are software, not hardware, like a wall socket. So, yes,

you have a much greater chance of being shocked by a wall socket than by a networking

socket.

Sockets are a key part of Unix and Windows-based operating systems. They make it easy for

software developers to create network-enabled programs. Instead of constructing network

connections from scratch for each program they write, developers can just include sockets in

their programs. The sockets allow the programs to use the operating system’s built-in

commands to handle networking functions. Because they are used for a number of different

network protocols (i.e. HTTP, FTP, telnet, and e-mail), many sockets can be open at one time.

how to configure DNS in windows O/S with the command or stepes….?

Netsh commands for Interface IP. You can use commands in the Netsh Interface IP context to

configure the TCP/IP protocol (including addresses, default gateways, DNS servers, and

WINS servers) and to display configuration and statistical information.

USE HELP COMMAND FOR MORE INFORMATION (netsh/?)

RARP:-

RARP is a TCP/ IP protocol term similar to ARP. RARP is the method that some machines use

to determine their own IP address. Essentially, a machine sends out a packet that includes a

machine hardware address. A server on the same network receives the packet and looks up

the hardware address. The server then sends back the associated IP address of that machine.

It is used for machines that do not have the capability to store their own IP addresses locally.

ARP:-

Address Resolution Protocol. ARP is the protocol used by IP (as in TCP/IP) for address

resolution. Address resolution refers to the ability of a station to resolve another station’s

MAC (hardware) address given its IP address.

When I ping an IP address the result comes out succesfull, but when I ping with host

name no result comes, ping fails. why?

On the network when you ping an IP address if ping request completed with 0% of loss that

mean you are able to reach that Device(ip address)

But when u ping hostname if u get the result as RTO that means Ping is been disabled for

hostname in firewall or router

If u get ping could not find the host address that means DNS issue.Mean Name resolution is

not happening.

Question 11

What is a full-class C in CIDR notation

CIDR specifies an IP address range using a combination of an IP address and its associated

network mask. CIDR notation uses the following format -

xxx.xxx.xxx.xxx/n

Full Class C in CIDR notation can be represented by

Example 10.16.0.0/16

This is a 256 class C = FIRST CLASS B

Now they here are a few more

10.16.0.0/17 is a 128 class C

10.16.0.0/16 is a 64 class C and so on.

Any comments are welcome

What the Purpose of VLAN?

VLANs can enhance network security.

VLANs increase the number of broadcast domains while decreasing their size.

Network adds, moves, and changes are achieved by configuring a port into the appropriate

VLAN.

A group of users needing high security can be put into a VLAN so that no users outside of the

VLAN can communicate with them.

As a logical grouping of users by function, VLANs can be considered independent from their

physical or geographic locations.

What is OSPF?

Open Shortest Path First

OSPF) is a non-proprietary link-state routing protocol limited to use with the TCP/IP stack.

Open Shortest Path First (OSPF) is an open standards routing protocol that’s been

implemented by a wide variety of network vendors, including Cisco. If you have multiple

routers and not all of them are Cisco, So your remaining options are basically RIPv1, RIPv2,

or OSPF. If it’s a large network, then, really, your only options are OSPF

OSPF provides the following features:

Consists of areas and autonomous systems

Minimizes routing update traffic

Allows scalability

Supports VLSM/CIDR

Has unlimited hop count

Allows multi-vendor deployment (open standard)

Characteristic of OSPF

Type of protocol - Link-state

Classless support - Yes

VLSM support - Yes

Auto summarization - No

Manual summarization - Yes

Discontiguous support - Yes

Route propagation - Multicast on change

Path metric - Bandwidth

Hop count limit - None

Convergence - Fast

Peer authentication - Yes

Hierarchical network - Yes (using areas)

Updates Event - Triggered

What is Spanning Tree protocol?

In a Layer 2 environment (switching or bridging), however, no routing protocols are used,

and active redundant paths are neither allowed nor desirable. Instead, some form of bridging

provides data transport between networks or switch ports. The Spanning Tree Protocol (STP)

provides network link redundancy so that a Layer 2 switched network can recover from

failures without intervention in a timely manner. It vigilantly monitors the network to find all

links, making sure that no loops occur by shutting down any redundant links. STP uses the

spanning-tree algorithm (STA) to first create a topology database, then search out and

destroy redundant links.

Difference between layer2 and layer3

Layer2:- It is used to send data using mac address and by frames.

Layer3:- It is used to send data using ip address and by packets

Network engineer interview questionsOSPF

Describe OSPF in your own words.

OSPF areas, the purpose of having each of them

Types of OSPF LSA, the purpose of each LSA type

What exact LSA type you can see in different areas

How OSPF establishes neighboor relation, what the stages are

If OSPF router is stucked in each stage what the problem is and how to troubleshoot

it

OSPF hierarchy in the single or multi areas. Cool OSPF behavior in broadcast and

nonbroadcast

Draw the diagram of typical OSPF network and explain generally how it works, DR,

BDR, election, ASBR, ABR, route redistribution and summarization

STP

How it works and the purpose

Diff types (SSTP, MSTP, RSTP) Cisco - PVST/PVST+

root election

Diff. port stages and timing for convergence

Draw the typical diagram and explain how diff types of STP work

What ports are blocking or forwarding

How it works if there are topology changes

ACLS

What are they

Diff types

Write an example if you want to allow and to deny…

Well-known port numbers (DNS - 53 and etc…)

QOS

What is that

What is the diff b/w L2 and L3 QoS

How it works

NETWORK:

Draw the typical network diagram you have to deal with

explain how it works

What part of it you are responsible

firewall, what is that, how it works, how it is diff from ACLs

What problems with the network you had had and how you solved it.

What are the ways to troubleshoot the network, techniques, commands

network security, ways to achieve it

SWITCHING:

VLANs

STP

How a L2 switch works with broadcast, unicast, multicast, known/unknown traffic

VRRP, GLBP

port monitoring and mirroring

L3 switch, how it works

PIM sparse and dense modes

Interview questions for network engineer

1. Describe the OSI model.

2. What is the difference between a repeater, bridge, router? Relate this to the OSI

model.

3. Describe an Ethernet switch and where it fits into the OSI model.

4. What is a VLAN? What is an ELAN? What is the difference?

5. Relate FDDI/ATM/SONET to the OSI model.

6. Explain how to configure a host network interface (e.g. IP address, netmask,

broadcast address)?

7. Describe Ethernet packet contents: min/max size, header.

8. Describe TCP/IP and its protocols.

9. Describe ATM and what are its current advantages and disadvantages.

10. Describe SONET.

11. What are the maximum distances for CAT5 cabling?

12. Describe UDP and TCP and the differences between the two.

13. What is your current IP address? Hoiw do you find that out on different OSs?

14. Describe what a broadcast storm is.

15. Describe what a runt, a giant, and a late collision are and what causes each of them.

16. How do you distinguish a DNS problem from a network problem?

17. Describe the Bandwidth Delay problem.

18. Describe the principle of multi-layer switching.

19. Describe the purpose and basic functionality of things like HSRP, VRRP etc.

#9 ATM is the short form for Asynchonous Transfer Mode.

Currently ATM is used in places where we require high speed data transfer. The ATM is a

technology of sending and recieving the packets and so it requires carriers such as

SONET/SDH etc. The packet size of the ATM packet is fixed and is 53 bytes.

Advantages

**********

1. As the packet size is fixed switching can be implemented in Hardware and so it is very fast.

2. The packet size small and constant so the latency is too small so that it can support real

time data transfer.

3. The ATM supports Quality of Service (QOS).

Disadvantages.

*************

1. The packet size is too small and if u take the additional header that is attached then it will

be huge. So the header size to the actual data send is less and so overhead is too much.

2. End to end is not ATM and so we still require ATM adapters and other equipments.

#2

Repeaters, bridges, and routers are devices used to link individual LANs together to form

larger internetworks. each one operates within a specific layer of the OSI model.

Repeaters operate at the Physical Layer of the OSI model. They simply listen to all network

traffic on one port and send it back out through one or more ports, extending smaller

networks into a larger, single network. A repeater simply receives frames, regenerates them,

and passes them along. It performs no processing of the frames or the data they contain.

Relation to OSI Layer Functions

Because repeaters operate at the Physical Layer, they do not need any addressing data from

the frame. Repeaters do not even look at the frames they are forwarding, passing along even

damaged frames. This can be especially problematic if one segment malfunctions and begins

a broadcast storm. All those erroneous broadcasts are forwarded faithfully by the repeater!

Bridges operate at the Data Link Layer. They use the Data Link Layer and its physical

addressing to join several networks into a single network efficiently.

Bridges join two or more network segments together, forming a larger individual network.

They function similarly to a repeater, except a bridge looks to see whether data it receives is

destined for the same segment or another connected segment. If the data is destined for a

computer on the same segment, the bridge does not pass it along. If that data is going to a

computer on another segment, the bridge sends it along.

Bridges use a routing table to determine whether data is destined for the local network or

not. On a bridge, the routing table contains MAC addresses. Each time the bridge receives

data, it looks in its routing table to see whether or not the data is destined for a node on the

local network. If it belongs to the local network, it does not forward the data. If it is not

destined for the local network, it looks in the routing table to determine which physical

network the destination address resides on, and sends the data out onto that network.

Bridges can not join dissimilar networks. If you have an Ethernet network and a Token Ring

network, you cannot use a bridge; you must use a router. However, a bridge can join

networks that use the same frame type but different media, just like a repeater.

Relation to OSI Layer Functions

Bridges work with the MAC sublayer of the Data Link Layer. Remember that the Data Link

Layer is concerned with communicating on the local network only. Bridges use information

from the MAC sublayer to make decisions on whether a packet is destined for the same

network or another network. The MAC address is used by bridges to determine first if the

destination is local or not, then to choose which connected network it must go to.

Router:

The Network Layer is concerned with network addressing for larger networks that consist of

many physical networks, often with multiple paths between them. Routers operate at the

Network Layer. They use the addressing information provided at the network level to join the

many networks together to form an internetwork.

Functions

Routers divide larger networks into logically designed networks. Routers may seem a lot like

bridges, but they are much smarter. Bridges cannot evaluate possible paths to the destination

to determine the best route. This can result in inefficient use of network resources. Bridges

also cannot use redundant paths. While two bridges can connect two networks, they risk

sending packets in an endless loop between the two networks. This behavior eventually

saturates the network, rendering it unusable.

The drawback to a router’s inherent intelligence is their speed. Because they

process so much information, routers tend to be slower than bridges.

Relation to OSI Layer Functions

Routers operate at the Network Layer of the OSI model. The Network Layer provides

addressing for internetworks, and routers use this addressing information to determine how

to pass along packets of data. Because routers operate at the Network Layer, they can link

different physical network topologies.

Vlan is virtual lan it used to put some interface in one broadcast domain and some interfaces in another,it used for security purpose and group departments, based on the mac address the vlan is configured in the switch ports

Multilayer switching

Multilayer switching is simply the combination of traditional Layer 2 switching with Layer 3

routing in a single product. Multilayer switching is new, and there is no industry standard yet

on nomenclature. Vendors, analysts, and editors don’t agree about the specific meaning of

terms such as multilayer switch, Layer 2 router, Layer 3 switch, IP switch, routing switch,

switching router, and wirespeed router. The term multilayer switch seems to be the best and

most widely used description of this class of product that performs both Layer 3 routing and

Layer 2 switching functions.

Multilayer switching is usually implemented through a fast hardware such as a higher-density

ASICs (Application-Specific Integrated Circuits), which allow real-time switching and

forwarding with wirespeed performance, and at lower cost than traditional software-based

routers built around general-purpose CPUs.

The following are some basic architecture approaches for the multiplayer switches:

Generic Cut-Through Routing: In the multi-layer switching architecture Layer 3 routing

calculations are done on the first packet in a data flow. Following packets belonging to the

same flow are switched at Layer 2 along the same route. In other words, route calculation

and frame forwarding are handled very differently here.

ATM-Based Cut-Through Routing - This is a variation of generic cut-through routing which is

based on ATM cells rather than frames. ATM-based cut-through routing offers several

advantages such as improved support of LAN emulation and multi-vendor support in the form

of the Multiprotocol Over ATM (MPOA) standard. Products referred to as IP switches and tag

switches generally fall into this category.

Layer 3 Learning Bridging CIn this architecture, routing is not provided. Instead, it uses IP

“snooping” techniques to learn the MAC/IP address relationships of endstations from true

routers that must exist elsewhere in the network. Then it redirects traffic away from the

routers and switches it based on its Layer 2 addresses.

Wirespeed Routing - Wirespeed architecture routes every packet individually. It is often

referred to as packet-by-packet Layer 3 switching. Using advanced ASICs to perform Layer 3

routing in hardware, it implements dynamic routing protocols such as OSPF and RIP. In

addition to basic IP routing, it supports IP multicast routing, VLAN segregation, and multiple

priority levels to assist in quality of service.

Q#12 - TCP is a connection oriented protocol which works on ACK based communication. It

provides error recovery & detection under Layer 4 of OSI model. Also, the TCP works in

reliable network which offers secured communication and no loss of data.

UDP is a User Datagram Protocol, used in a faster network. No ACK is required for the data

sent to the network. Also, the application like TFTP prefers using UDP for its transport layer

communication. Its a connectionless protocol.

#11Each A-Net component in a system can have up to 500 feet (150 meters) of Category 5e cable (UTP, Unshielded Twisted Pair) between it and the next A-Net component (for example, from a Input Module to a Personal Mixer, or from one Personal Mixer to another in series). Cat-5e cable comes in two varieties, stranded and solid. Stranded wire is more flexible, but may not perform as well as solid wire at extreme distances. The number of components in the system is unlimited. #11Each A-Net component in a system can have up to 500 feet (150 meters) of Category

5e cable (UTP, Unshielded Twisted Pair) between it and the next A-Net component (for example, from a Input Module to a Personal Mixer, or from one Personal Mixer to another in series). Cat-5e cable comes in two varieties, stranded and solid. Stranded wire is more flexible, but may not perform as well as solid wire at extreme distances. The number of components in the system is unlimited.conigure.network adrees mask and broad castrouter>enablerouter#config trouter(config)#interface ethernet0/0router(config-if)#ip adreess 10.0.0.2 255.0.0.0router(config)#no shutrouter(config)#exitrouter(config)#interface serial0router(config-if)#ip adreess 20.0.0.2 255.0.0.0router(config-if)no shutrouter(config-if)#clock rate 6400router(config-if)#exitby this comand we can assign n/w adreess and ip mask.cisco says invalid to broad cast adreess but rule can be broken by applyong comand#ip-subnet zero

Network engineer/architect interview questions

1. Explain how traceroute, ping, and tcpdump work and what they are used for?

2. Describe a case where you have used these tools to troubleshoot.

3. What is the last major networking problem you troubleshot and solved on your own in

the last year?

4. What LAN analyzer tools are you familiar with and describe how you use them to

troubleshoot and on what media and network types.

5. Explain the contents of a routing table (default route, next hop, etc.)

6. What routing protocols have you configured?

7. Describe the commands to set up a route.

8. What routing problems have you troubleshot?

9. How do you display a routing table on a Cisco? On a host?

10. How do you use a routing table and for what?

11. What is a route flap?

12. What is a metric?

13. When do you use BGP, IGRP, OSPF, Static Routes?

14. What do you see as current networking security issues (e.g. NFS mounting, spoofing,

one time passwords, etc.)?

15. Describe a routing filter and what it does.

16. Describe an access list and what it does.

17. What is a network management system?

18. Describe how SNMP works.

19. Describe the working environment you are currently in, e.g. frequent interruptions,

frequent priority shifting, team or individual.

20. What do you use to write documentation? Editor? Mail reader?

21. What platform (s) do you currently work on at your desk?

22. How do you manage multiple concurrent high level projects?

23. Describe a recent short term stressful situation and how you managed it.

24. How do you manage a long term demanding stressful work environment?

25. Have you worked in an assignment based environment, e.g. work request/trouble

ticket system, and if so, describe that environment.

26. Describe what network statistics or measurement tools you are familiar with and how

you have used them.

27. Describe what a VPN is and how it works.

28. Describe how VoIP works.

29. Describe methods of QoS.

30. How does ToS bit work?

CCNA/Cisco admin interview questions

1. You need to retrieve a file from the file server for your word processing

application, which layer of the OSI model is responsible for this function?

A. Presentation layer

B. Application layer

C. Session layer

D. Transport layer

E. Datalink layer

2. You are working in a word processing program, which is run from the file

server. Your data comes back to you in an unintelligible manner. Which layer

of the OSI model would you investigate?

A. Application layer

B. Presentation layer

C. Session layer

D. Network layer

E. Datalink layer

3. The IEEE subdivided the datalink layer to provide for environments that need

connectionless or connection-oriented services. What are the two layers

called?

A. Physical

B. MAC

C. LLC

D. Session

E. IP

4. You are working with graphic translations. Which layer of the OSI model is

responsible for code formatting and conversion and graphic standards.

A. Network layer

B. Session layer

C. Transport layer

D. Presentation layer

5. Which is the best definition of encapsulation?

A. Each layer of the OSI model uses encryption to put the PDU from the upper

layer into its data field. It adds header and trailer information that is available

to its counterpart on the system that will receive it.

B. Data always needs to be tunneled to its destination so encapsulation must be

used.

C. Each layer of the OSI model uses compression to put the PDU from the upper

layer into its data field. It adds header and trailer information that is available

to its counterpart on the system that will receive it.

D. Each layer of the OSI model uses encapsulation to put the PDU from the

upper layer into its data field. It adds header and trailer information that is

available to its counterpart on the system that will receive it.

6. Routers can be configured using several sources. Select which of the

following sources can be used.

A. Console Port

B. Virtual Terminals

C. TFTP Server

D. Floppy disk

E. Removable media

7. Which memory component on a Cisco router contains the dynamic system

configuration?

A. ROM

B. NVRAM

C. Flash

D. RAM/DRAM

8. Which combination of keys will allow you to view the previous commands that

you typed at the router?

A. ESC-P

B. Ctrl-P

C. Shift-P

D. Alt-P

9. Which commands will display the active configuration parameters?

A. show running-config

B. write term

C. show version

D. display term

10. You are configuring a router, which prompt tells you that you are in the

privileged EXEC mode?

A. @

B. >

C. !

D. :

E. #

11. What does the command “IP name-server 255.255.255.255″ accomplish?

A. It disables domain name lookup.

B. It sets the domain name lookup to be a local broadcast.

C. This is an illegal command.

D. The command is now defunct and has been replaced by “IP server-name ip

any”

12. The following selections show the command prompt and the configuration of

the IP network mask. Which two are correct?

A. Router(config-if)#netmask-format { bitcount | decimal | hexadecimal }

B. Router#term IP netmask-format { bitcount | decimal | hexadecimal }

C. Router(config-if)#IP netmask-format { bitcount | decimal | hexadecimal }

D. Router#ip netmask-format { bitcount | decimal | hexadecimal }

13. Which layer is responsible for flow control with sliding windows and

reliability with sequence numbers and acknowledgments?

A. Transport

B. Application

C. Internet

D. Network Interface

14. Which processes does TCP, but not UDP, use?

A. Windowing

B. Acknowledgements

C. Source Port

D. Destination Port

15. Select which protocols use distance vector routing?

A. OSPF

B. RIP

C. IGRP

D. PPP

1.22. 13. 3,44. 45. 26. 1,2,37. 48. 29. 110. 511. 412. 313. 114. 115. 2,3

3: 2,34: 45: 46: 1,27: 48: 29: 110: 513: 114: 1,215: 2,3

1) 22) 33) 2&34) 45) 46) 1&27) 28) 39) 1&310) 511) 212) 1&313) 114) 1&215) 2

1.22.23.2,34.45.46.1,27.28.29.110.511.41213.114.215.2,3

1) 22) 13) 2,34) 45) 46) 17) 38) 29) 110) 511) 312) 313) 114) 1,2,415) 2,3

2) 23) 2&34) 45) 46) 1&27) 48) 29) 1&310) 511) 312) 3

1) 52) 4

3) 2&34) 45) 36) 17) 48) 29) 110)3

1.22.33.24.45.4

6.1,2,37.28.29.1

10.511.3

13) 114) 1&215) 2&3

11)213) 114)115)2

12.313.114.115.1

Networking and protocols interview questions

Q: In the TCP client-servel model, how does the three-way handshake work in

opening connection?

A: The client first sends a packet with sequence "x" to the server. When the server receives

this packet, the server will send back another packet with sequence "y", acknowledging the

request of the client. When the client receives the acknowledgement from the server, the

client will then send an acknowledge back to the server for acknowledging that sequence "y"

has been received.

Q: What is the purpose of exchanging beginning sequence numbers during the the

connection in the TCP client-server model?

A: To ensure that any data lost during data transfer can be retransmitted.

Q: How does Asynchronous Transfer Mode (ATM) work?

A: ATM works by transmitting all traffic in small, fixed-sized cells. These small, fixed-size cells

reduces queuing delay and can be switched quickly. ATM fits into layer 2 of the OSI model

and provides functions for framing and error correction. At the port interface, ATM switches

convert cells into frames, and vice versa. ATM provides Quality of Service and traffic shaping.

Q: Given a Class B Network with subnet mask of 255.255.248.0 and a packet

addressed to 130.40.32.16, what is the subnet address?

A: Take the 2 addresses, write them in binary form, then AND them. The answer is

130.40.32.0

This is regarding the question :-

Q: Given a Class B Network with subnet mask of 255.255.248.0 and a packet addressed to

130.40.32.16, what is the subnet address?

As the solution mentions, we need to AND the mask and IP. The first two octets we know

represent the network address of the class B IP. From the given mask, in the third octet,

there are five bits for the sub-network, meaning the subnetwork of the given IP has the value

16. So the sub-network would be 130.40.16.x .

The mentioned answer 130.40.32.0 would be true if the third octet in the mask was 255.

Comments welcome.

Networking interview questions

Q1. Name of seven layers in Open System Interconnection model.

A. They are Application, Presentation, Session, Transport, Network, Data link, and Physical.

Q2. What is the time complexity of matrix multiplication ?

void Mult_Matrix(matrix A, matrix B, matrix C)

{

int i, j, k;

for ( i = 1; i < N; i++)

for ( j = 1; j < N; j++ )

{

C[i][j] = 0;

for ( k = 0; k < N; k++ )

C[i][j] = A[i][j]*B[k][j];

}

retrun;

}

A. The time comlexity of matrix mulitiplication is O(N^3)

Q3. What is the null pointer in C++ ?

A. The null pointer is a special C++ pointer value that can be used for any pointer that

doesn’t pointer anywhere. It can be written as the constant NULL form stlib.h

Q4. What is the goal of the shortest distance algorithm ?

A. The goal is to completely fill the distance array so that for each vertex v, the value of

distance[v] is the weight of the shortest path from start to v.

Q5. What is the difference between an abstract class and an interface?

A.

An abstract class may have fields and some implemented methods.

An interface has no implementation; only constants and method declarations.

Network programming interview questions

Question 1: How does the race condition occur?

It occurs when two or more processes are reading or writing some shared data and the final

result depends on who runs precisely when.

Question 2: What is multiprogramming?

Multiprogramming is a rapid switching of the CPU back and forth between processes.

Question 3: Name the seven layers of the OSI Model and describe them briefly.

Physical Layer - covers the physical interface between devices and the rules by which bits are

passed from one to another.

Data Link Layer - attempts o make the physical link reliable and provides the means to

activate, maintain, and deactivate the link.

Network Layer - provides for the transfer of information between end systems across

some sort communications network.

Transport Layer - provides a mechanism for the exchange of data between end system.

Session Layer - provides the mechanism for controlling the dialogue between applications

in end systems.

Presentation Layer - defines the format of the data to be exchanged between applications

and offers application programs a set of data transformation services.

Application Layer - provides a means for application programs to access the OSI environment.

Question 4: What is the difference between TCP and UDP?

TCP and UDP are both transport-level protocols. TCP is designed to provide reliable

communication across a variety of reliable and unreliable networks and internets.

UDP provides a connectionless service for application-level procedures. Thus, UDP is

basically

an unreliable service; delivery and duplicate protection are not guareented.

Question 5: What does a socket consists of?

The combination of an IP address and a port number is called a socket.

Question:1Refer to the exhibit. An organization connects two locations, supporting two VLANs,

through two switches as shown. Inter-VLANs communication is not required. The network is working properly and there is full connectivity. The organization needs to add additional VLANs, so it has been decided to implement VTP. Both switches are configured as VTP servers in the same VTP domain. VLANs added to Switch1 are not learned by Switch2. Based on this information and the partial configurations in the exhibit, what is the problem?

A.Switch2 should be configured as a VTP client.B.VTP is Cisco proprietary and requires a different trunking encapsulation.C.A router is required to route VTP advertisements between the switches.D.STP has blocked one of the links between the switches,limiting connectivity.E.The links between the switches are access links.

Answer: D

Question:2Refer to the exhibit.What is the meaning of the output MTU 1500 bytes?

A.The maximum number of bytes that can traverse this interface per second is 1500.B.The minimum segment size that can traverse this interface is 1500 bytes.C.The maximum segment size that can traverse this interface is 1500 bytes.D.The minimum packet size that can traverse this interface is 1500 bytes.E.The maximum packet size that can traverse this interface is 1500 bytes.F.The maximum frame size that can traverse this interface is 1500 bytes.

Answer: E

Question:3Which statement is correct about the internetwork shown in the diagram?

A.Switch 2 is the root bridge.B.Spaning Tree is not runing.C.Host D and Server 1 are in the same network.D.No collisions can occur in traffic between Host B and Host C.E.If Fa0/0 is down on Router1, Host A cannot access Server1.F.If Fa0/1 is down on Switch3, Host C cannot access Server2.

Answer: C

Question:4Refer to the digram.What is the largest configuration file that can be stored on this router?

A.191K bytesB.16384K bytes

C.31369K bytesD.114688K bytes

Answer: A

Question:5Refer to the exhibit.Which command will created a default route on Router B to reach all networks beyond routerA?

A.ip route 0.0.0.0 0.0.0.0 192.168.2.2B.ip route 192.168.1.0 255.255.255.0 192.168.2.1C.ip route 192.168.1.0 255.255.255.0 s0/0/0D.ip route 10.0.0.0 255.255.255.0 s0/0/0E.ip route 0.0.0.0 255.255.255.0 192.168.2.2

Answer: A

Question:6Refer to the exhibit Hosts in network 192.168.2.0 are unable to reach hosts in network 192.168.3.0.Based on the output from RouterA, what are two possible reasons for the failure?(Choose two)

A.The cable that is connected to S0/0 on RouterA is faulty.B.Interface S0/0 on RouterB is administratively down.C.Interface S0/0 on RouterA is configured with an incorrect subnet mask.D.The IP address that is configured on S0/0 of RouterB is not in the correct subnet.E.Interface S0/0 on RouterA is not receiving a clock signal from the CSU/DSU.F.The encapsulation that is configured on S0/0 of RouterB does not match the encapsulation that is configured on S0/0 of RouterA.

Answer: E, F

Question:7Exhibit:

A.

Answer: A

Question:8Refer to the exhibit. Which switch provides the spanning-tree designated port role for the network segment that services the printers?

A.Switch1B.SWitch2

C.Switch3D.Switch4

Answer: A

Question:9Refer to the exhibit. The network is converged.After link-state advertisements are received from Router_A, what information will Router_E contain in its routing table for the subnets 208.149.23.64 and 208.149.23.96?

A. 208.149.23.64[110/13] via 190.173.23.10,00:00:07, FastEthemet0/0208.149.23.96[110/13] via 190.173.23.10,00:00:16, FastEthemet0/0B. 208.149.23.64[110/1] via 190.172.23.10,00:00:07, Serial1/0208.149.23.96[110/3] via 190.173.23.10,00:00:16, FastEthemet0/0C. 208.149.23.64[110/13] via 190.173.23.10,00:00:07, Serial1/0208.149.23.96[110/13] via 190.173.23.10,00:00:16, Serial1/0208.149.23.96[110/13] via 190.173.23.10,00:00:16, FastEthemet0/0D. 208.149.23.64[110/3] via 190.172.23.10,00:00:07, Serial1/0208.149.23.96[110/3] via 190.173.23.10,00:00:16, Serial1/0

Answer: A

Question:10Exhibit:

A.

Answer: A

Question:11An administrator issues the command ping 127.0.0.1 from the command line prompt on a PC. If a reply is received, what does this confirm?

A.The PC has connectivity with a local host.B.The PC has connectivity with a Layer 3 device.C.The PC has a default gateway correctly configuredD.The PC has connectivity up to Layer 5 of the OSI model.E.The PC has the TCP/IP protocol stack correctly imstalled.

Answer: E

Question:12What is the maximum data rate specified for IEEE 802.11b WLANs?

A.10 MbpsB.11 Mbps

C.54 MbpsD.100 Mbps

Answer: B

Question:13Refer to the exhibit. Host A is to send data to Host B. How will Router1 handle the data frame received from Host A? (Choose three.)

A. Router1 will strip off the source MAC address and replace it with the MAC address on the forwarding FastEthernet interface.B. Router1 will strip off the source IP address and replace it with the IP address on the forwarding FastEthernet interface.C. Router1 will strip off the destination MAC address and replace it with the MAC address of Host B.D. Router1 will strip off the destination IP address and replace it with the IP address of Host B.E. Router1 will forward the data frame out interface FastEthernet0/1.F. Router1 will forward the data frame out interface FastEthernet0/2.

Answer: A,C,F

Question:14What should be done prior to backing up an IOS image to a TFTP server? (Choose three.)

A. Make sure that the server can be reached across the network.B. Check that authentication for TFTP access to the server is set.C. Assure that the network server has adequate space for the IOS image.D. Verify file naming and path requirements.E. Make sure that the server can store binary files.F. Adjust the TCP window size to speed up the transfer.

Answer: A,C,D

Question:15A network associate is trying to understand the operation of the FLD Corporation by studying the network in the exhibit. The associate knows that the server in VLAN 4 provides the necessary resources to support the user hosts in the other VLANs. The associate needs to determine which interfaces are access ports. Which interfaces are access ports? (Choose three.)

A. Switch1 – Fa 0/2B. Switch1 – Fa 0/9C. Switch2 – Fa 0/3D. Switch2 – Fa 0/4

E. Switch2 – Fa 0/8F. Router – Fa 1/0

Answer: A,C,D

Question:16The show interfaces serial 0/0 command resulted in the output shown in the graphic. What are possible causes for this interface status? (Choose three.)

A. The interface is shut down.B. No keepalive messages are received.C. The clockrate is not set.D. No loopback address is set.E. No cable is attached to the interface.F. There is a mismatch in the encapsulation type.

Answer: B,C,F

Question:17Refer to the partial command output shown. Which two statements are correct regarding the router hardware? (Choose two.)

A. Total RAM size is 32 KB.B. Total RAM size is 16384 KB (16 MB).C. Total RAM size is 65536 KB (64 MB).D. Flash size is 32 KB.E. Flash size is 16384 KB (16 MB).F. Flash size is 65536 KB (64 MB).

Answer: C,E

Question:18Refer to the exhibit. A network administrator configures a new router and enters the copy starup-config running-config command on the router. The network administrator powers down the router and sets it up at a remote location. When the router starts, it enters the system configuration dialog as shown. What is the cause of the problem?

A. The network administrator failed to save the configuration.B. The configuration register is set to 0*2100.C. The boot system flash command is missing from the configuration.D. The configuration register is set to 0*2102.E. The router is configured with the boot system startup command.

Answer: A

Question:19Which routing protocols can be used within the enterprise network shown in the diagram? (Choose three.)

A. RIP v1B. RIP v2C. IGRPD. OSPFE. BGPF. EIGRP

Answer: B,D,F

Question:20A network administrator needs to allow only one Telnet connection to a router. For anyone viewing the configuration and issuing the show run command, the password for Telnet access should be encrypted. Which set of commands will accomplish this task?

A.service password-encryptionaccess-list1 permit 192.168.1.0.0.0.0.255loginpassword ciscoaccess-class 1B.enable password secretline vty0loginpassword ciscoC.service password-encryptionline vty0loginpassword ciscoD.service password-encryptionline vty0 4loginpassword cisco

Answer: C