Produced by: Robb Jones [email protected] and/or [email protected] Frederick County Career & Technology Center Cisco Networking Academy Frederick County Public Schools Frederick, Maryland, USA Special Thanks to Melvin Baker and Jim Dorsch for taking the time to check this workbook for errors.
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Class A 1 – 127 (Network 127 is reserved for loopback and internal testing)Leading bit pattern 0 00000000.00000000.00000000.00000000
Class B 128 – 191 Leading bit pattern 10 10000000.00000000.00000000.00000000
Class C 192 – 223 Leading bit pattern 110 11000000.00000000.00000000.00000000
Class D 224 – 239 (Reserved for multicast)
Class E 240 – 255 (Reserved for experimental, used for research)
Private Address Space
Class A 10.0.0.0 to 10.255.255.255
Class B 172.16.0.0 to 172.31.255.255
Class C 192.168.0.0 to 192.168.255.255
Default Subnet Masks
Class A 255.0.0.0
Class B 255.255.0.0
Class C 255.255.255.0
Network . Host . Host . Host
Network . Network . Host . Host
Network . Network . Network . Host
Inside Cover
This workbook assumes you already have a background in subnetting. If you don’t you maywant to consider completing the IP Addressing and Subnetting Workbook.
Frederick County Career & Technology CenterCisco Networking Academy
Frederick County Public SchoolsFrederick, Maryland, USA
Special Thanks to Melvin Baker and Jim Dorschfor taking the time to check this workbook for errors.
Workbooks included in the series:
IP Addressing and Subnetting WorkbooksACLs - Access Lists Workbooks
VLSM Variable-Length Subnet Mask IWorkbooks
Classful vs. ClasslessSubnetting
When you’re subnetting an IP address for a network you have twooptions: classful and classless. Classful subnetting is the simplest method.It tends to be the most wasteful because it uses more addresses than arenecessary. In classful subnetting you use the same subnet mask for eachsubnet, and all the subnets have the same number of addresses in them.
Classless addressing allows you to use different subnet masks andcreate subnets tailored to the number of users in each group. This techniqueis referred to as VLSM.
What is VLSM
Variable Length Subnet Masks allow you a much tighter control overyour addressing scheme. If you use a class C address with a default subnetmask you end up with one subnet containing 256 addresses. By using VLSMyou can adjust the number of subnets and number of addresses dependingon the specific needs of your network. The same rules apply to a class A orB addresses.
VLSM is supported by the following protocols: RIP version 2, OSPF,EIGRP, Dual IS-IS, and BGP,. You need to configure your router for VariableLength Subnet Masking by setting up one of these protocols. Then configurethe subnet masks of the various interfaces in the IP address interface sub-command.
Benefits of VLSM
Allows efficient use of address spaceAllows the use of multiple subnet mask lengthsBreaks up an address block into smaller custom blocksAllows for route summarizationProvides more flexibility in network designSupports hierarchical enterprise networks
This workbook explores three different methods to figure out sub-subnets:the box method, the circle method, and a VLSM chart.
1
Classful SubnettingExample
When you’re subnetting an IP address for a network you have twooptions: classful and classless. Classful subnetting is the simplest method.It also tends to be the most wasteful because it uses more addresses thanare necessary. In classful subnetting you use the same subnet mask foreach subnet, and all the subnets have the same number of addresses inthem.
In this example you need five subnets, each one containing 30 hosts.The serial connections only require two address each so you are wasting 28usable addresses in each of the serial subnet ranges.
Classless addressing allows you to use different subnet masksand create subnets tailored to the number of users in each subnetwork.There are fewer wasted IP addresses using smaller subnets.
In this example you need at total of five subnets, two containing 30hosts, one containing 12 hosts, and two serial connections that only requiretwo addresses each.
By adjusting the subnet masks you can cut your address usage byalmost half in this example. This type of subnetting requires a networkprotocol which will support it such as: RIP version 2, EIGRP, OSPF, or BGP.
Start with a square. The whole squareis a single subnet comprised of 256addresses.
Visualizing Subnets UsingThe Box Method
The box method is a simple way to visualize the breakdown of subnetsand addresses into smaller sizes. By shading or coloring in the boxes youcan easily break up your subnets without overlapping your addresses. Youadjust each subnet to the correct size needed.
/25255.255.255.128
128 Hosts2 Subnets
/26255.255.255.192
64 Hosts4 Subnets
4
Split the box in half and you get twosubnets with 128 addresses.
Divide the box into quarters and youget four subnets with 64 addresses.
5
/27255.255.255.224
32 Hosts8 Subnets
Split each individual square and youget eight subnets with 32 addresses.
/30255.255.255.252
4 Hosts64 Subnets
/29255.255.255.248
8 Hosts32 Subnets
/28255.255.255.240
16 Hosts16 Subnets
Split the boxes in half again and youget sixteen subnets with sixteenaddresses.
The next split gives you thirty twosubnets with eight addresses.
The last split gives sixty four subnetswith four addresses each.
Color in the squares used with differentshades to highlight each subnet.
VLSM AddressingBox Method
(Sample)
Problem 1Using the network diagram and information given create an addressing
scheme which utilizes variable-length subnet masks. Show the subnetaddress and CIDR in the boxes below, color or shade the sub-subnets used inthe box. This business will be using the class C address 220.10.10.0. Re-member to start with your largest groups first.
MarketingDepartment
60 Hosts
LAN Address:
220.10.10.0/26
ResearchDepartment
28 Hosts
LAN Address:
220.10.10.64/27
0
255127
128
6364
95
96
6
VLSM AddressingBox Method
(Sample)
Problem 2Using the network diagram and information given create an addressing
scheme which utilizes variable-length subnet masks. Show the subnetaddress and CIDR in the boxes below, color or shade the sub-subnets used inthe box. This company will be using the class C address 192.168.16.0. Re-member to start with your largest groups first.
Washington D.C.120 Hosts
Frederick20 Hosts
Baltimore60 Hosts
0
255127
128
192191
223
LAN Address:
192.168.16.0/25
LAN Address:
192.168.16.192/27LAN Address:
192.168.16.128/26
WAN Address #1:
192.168.16.224/30 WAN Address #2:
192.168.16.228/30
227
239231
224 232
228
240
Color in the squares used with differentshades to highlight each subnet.
7
8
VLSM AddressingBox Method
Problem 3Using the network diagram and information given create an addressing
scheme which utilizes variable-length subnet masks. Show the subnetaddress and CIDR in the boxes below, color or shade the sub-subnets used inthe box. This company will be using the class C address 190.10.10.0. Re-member to start with your largest groups first.
Dallas60 Hosts
Ft. Worth25 Hosts
LAN Address:
LAN Address:
WAN Address #1:
Color in the squares used with differentshades to highlight each subnet.
0
255
128
6364
95
96
99
103 111
127
104
100
112
VLSM AddressingBox Method
Problem 4Using the network diagram and information given create an addressing
scheme which utilizes variable-length subnet masks. Show the subnetaddress and CIDR in the boxes below, color or shade the sub-subnets used inthe box. This company will be using the class C address 220.108.38.0. Re-member to start with your largest groups first.
Corpus Christi25 Hosts
Waco50 Hosts
Houston120 Hosts
LAN Address:
LAN Address:LAN Address:
WAN Address #1:WAN Address #2:
Color in the squares used with differentshades to highlight each subnet.
9
0 12832 160
15 4739 175167135 1437
11 4335 171163131 1393
27 5951 187179147 15519
31 6355 191183151 15923
75 10799 235227195 20367
79 111103 239231199 20771
91 123115 251243211 21983
95 127119 255247215 22387
408 136 168
4 13236 1644412 140 172
16 14448 1765624 152 184
20 14852 1806028 156 188
64 19296 22410472 200 232
68 196100 22810876 204 236
80 208112 24012088 216 248
84 212116 24412492 220 252
10
VLSM AddressingBox Method
Problem 5Using the network diagram and information given create an addressing
scheme which utilizes variable-length subnet masks. Show the subnetaddress and CIDR in the boxes below, color or shade the sub-subnets usedin the box. This company will be using the class C address 192.168.10.0.Remember to start with your largest groups first.
New York115 Hosts
Fargo23 Hosts
LAN Address:
LAN Address:
WAN Address #2:
Color in the squares used with differentshades to highlight each subnet.
San Jose
12 Hosts
48 Hosts
LAN Address:
LAN Address:
WAN Address #1:
0 12832 160
15 4739 175167135 1437
11 4335 171163131 1393
27 5951 187179147 15519
31 6355 191183151 15923
75 10799 235227195 20367
79 111103 239231199 20771
91 123115 251243211 21983
95 127119 255247215 22387
408 136 168
4 13236 1644412 140 172
16 14448 1765624 152 184
20 14852 1806028 156 188
64 19296 22410472 200 232
68 196100 22810876 204 236
80 208112 24012088 216 248
84 212116 24412492 220 252
VLSM AddressingBox Method
Problem 6Using the network diagram and information given create an addressing
scheme which utilizes variable-length subnet masks. Show the subnetaddress and CIDR in the boxes below, color or shade the sub-subnets usedin the box. This company will be using the class C address 222.10.150.0.Remember to start with your largest groups first.
Boston
LAN Address:
WAN Address #1:
Draw the necessary lines and color in the used squareswith different shades to highlight each subnet.
11
London
WAN Address #2:
6 Hosts
12 Hosts
LAN Address:
24 Hosts 37 Hosts
LAN Address:
LAN Address:
0
255
128
6364 192
191
32
31
95
96159
223
224
160
127
Toyko
12
VLSM AddressingBox Method
Problem 7Using the network diagram and information given create an addressing
scheme which utilizes variable-length subnet masks. Show the subnetaddress and subnet mask in the boxes below, color or shade the sub-subnetsused in the box. This company will be using the class C address 200.150.70.0.Remember to start with your largest groups first.
Draw the necessary lines and color in the used squareswith different shades to highlight each subnet.
Boston 2
LAN Address:
6 Hosts
12 Hosts
LAN Address:
LAN Address:
14 Hosts
LAN Address:
25 Hosts
0
255127
128
6364 192
191
Serial Address:
Boston 1
VLSM AddressingBox Method
Problem 8Using the network diagram and information given create an addressing
scheme which utilizes variable-length subnet masks. Show the subnetaddress and subnet mask in the boxes below, color or shade the sub-subnetsused in the box. This company will be using the class C address 192.168.24.0.Remember to start with your largest groups first.
LAN Address:
Draw the necessary lines and color in the used squareswith different shades to highlight each subnet.
13
London
WAN Address #2:
18 Hosts
LAN Address:
95 Hosts 12 Hosts
LAN Address:
LAN Address:
0
34 Hosts
255
WAN Address #1:
Paris
New York
/24255.255.255.0
256 Hosts1 Subnet
Start with a circle. The whole circle isa single subnet comprised of 256addresses.
Visualizing Subnets UsingThe Circle Method
The circle method is another method used to visualize the breakdownof subnets and addresses into smaller sizes. By shading or coloring in thedifferent sections of the circle you can easily break up your subnets withoutoverlapping your addresses. You adjust each subnet to the correct sizeneeded.
/25255.255.255.128
128 Hosts2 Subnets
/26255.255.255.192
64 Hosts4 Subnets
Split the circle in half and you get twosubnets with 128 addresses.
Divide the circle into quarters andyou get four subnets with 64addresses.
.0
.127.128
.255
.0
.127.128
.255
.63
.64.191.192
14
/27255.255.255.224
32 Hosts8 Subnets
Split each quarter and you get eightsubnets with 32 addresses.
/30255.255.255.252
4 Hosts64 Subnets
/29255.255.255.248
8 Hosts32 Subnets
/28255.255.255.240
16 Hosts16 Subnets
Split the boxes in half again and youget sixteen subnets with sixteenaddresses.
The next split gives you thirty twosubnets with eight addresses.
The last split gives sixty four subnetswith four addresses each.
.0
.127.128
.255
.63
.64.191.192
.31.32
.95.96.159
.160
.223.224
.0
.31
.15.16
.64
.63
.48.47
.32
.111
.96.95
.80.79
.112.127
.176
.224
.223
.192
.208
.207
.191
.175
.159
.143
.160
.144
.128
.255
.239.240
15
.0 -
.7
.24
- .31.8
- .1
5.1
6 - .
23
.64 - .71
.56 - .63
.48 - .55.40 - .4
7.32 -
.39
.104 - .111.96 - .103
.88 - .95
.80 - .87
.72 - .79
.112 - .119
.120 - .127
.176 - .183
.224
- .23
1
.216 - .223
.192 - .199
.208 - .215
.200 - .207
.184 - .191
.168. - 175
.152 - .159
.136 - .143
.160 - .167 .144 - .151
.128 - .135
.248
- .2
55
.232
- .2
39
.240
- .2
47
.0 -
.3
.24 -
.27
.8 -
.11
.16
- .19
.64 - .67
.56 - .59
.48 - .51
.40 - .43
.32 -
.35
.104 - .107.96 - .99
.88 - .91
.80 - .83
.72 - .75
.112 - .115
.120 - .123.176 - .179
.224
- .22
7
.216 - .219
.192 - .195
.208 - .211
.200 - .203
.184 - .187
.168. - 171
.152 - .155 .136 - .139
.160 - .163
.144 - .147
.128 - .131
.248
- .2
51
.232
- .2
35
.240
- .2
43 .4 -
.7
.12
- .15
.20
- .23
.28 -
.31
.36 - .39
.44 - .47
.52 - .55
.60 - .63
.68 - .71
.76 - .79
.84 - .87.92 - .95
.100 - .103
.108 - .111
.116 - .119
.124 - .127
.132 - .135
.140 - .143
.148 - .151.156 - .159
.164 - .167
.172. - 175
.180 - .183
.188 - .191
.196 - .199
.204 - .207.212 - .2
15.22
0 - .2
23 .228
- .23
1
.236
- .2
39
.244
- .2
47
.252
- .2
55
16
Color in the necessary circle sections used with differentshades to highlight each subnet.
VLSM AddressingCircle Method
(Sample)
Problem 9Using the network diagram and information given create an addressing
scheme which utilizes variable-length subnet masks. Show the subnetaddress and CIDR in the circle below, color or shade the sub-subnets used.This business will be using the class C address 220.10.10.0.Remember to start with your largest groups first.
MarketingDepartment
60 Hosts
LAN Address:
220.10.10.0/26
ResearchDepartment
28 Hosts
LAN Address:
220.10.10.64/27
.0.255
.127.128
.96
.63
.95
.64
17
VLSM AddressingCircle Method
(Sample)
Problem 10Using the network diagram and information given create an addressing
scheme which utilizes variable-length subnet masks. Show the subnetaddress and CIDR in the circle below, color or shade the sub-subnets used.This company will be using the class C address 192.168.16.0.Remember to start with your largest groups first.
Washington D.C.120 Hosts
Frederick20 Hosts
Baltimore60 Hosts
LAN Address:
192.168.16.0/25
LAN Address:
192.168.16.192/27LAN Address:
192.168.16.128/26
WAN Address #1:
192.168.16.224/30 WAN Address #2:
192.168.16.228/30
Color in the necessary circle sections used with differentshades to highlight each subnet.
.255.240
.232
- .2
39
.0
.127
.191
.128
.223
.192
.224 -
.227
.228
- .23
1
.0
18
Color in the necessary circle sections used with differentshades to highlight each subnet.
VLSM AddressingCircle Method
Problem 11Using the network diagram and information given create an addressing
scheme which utilizes variable-length subnet masks. Show the subnetaddress and CIDR in the circle below, color or shade the sub-subnets used.This business will be using the class C address 200.20.20.0.Remember to start with your largest groups first.
MarketingDepartment
50 Hosts
LAN Address:
Department25 Hosts
LAN Address:
MarketingDepartment100 Hosts
LAN Address:
.224
.255
.127
.191
.128
.223
.192
19
VLSM AddressingCircle Method
Problem 12Using the network diagram and information given create an addressing
scheme which utilizes variable-length subnet masks. Show the subnetaddress and CIDR in the circle below, color or shade the sub-subnets used.This company will be using the class C address 199.55.70.0.Remember to start with your largest groups first.
Color in the necessary circle sections used with differentshades to highlight each subnet.
LAN Address:
New York
21 Hosts
LAN Address:
115 Hosts 8 Hosts
LAN Address:
LAN Address:
12 Hosts
WAN Address #1:
Boston.0
- .3
.24
- .27
.8 -
.11
.16
- .19
.64 - .67
.56 - .59
.48 - .51
.40 - .43.32
- .35
.104 - .107.96 - .99
.88 - .91
.80 - .83
.72 - .75
.112 - .115
.120 - .123
.176 - .179
.224 -
.227
.216 - .219
.192 - .195
.208 - .211
.200 - .203
.184 - .187
.168. - 171
.152 - .155
.136 - .139
.160 - .163 .144 - .147
.128 - .131
.248
- .2
51
.232
- .23
5
.240
- .2
43
.4 -
.7
.12
- .15
.20
- .23
.28 -
.31
.36 - .39
.44 - .47
.52 - .55
.60 - .63
.68 - .71
.76 - .79.84 - .87.92 - .95
.100 - .103
.108 - .111
.116 - .119
.124 - .127
.132 - .135
.140 - .143.148 - .151
.156 - .159
.164 - .167
.172. - 175
.180 - .183
.188 - .191
.196 - .199
.204 - .207.212 - .2
15 .220 -
.223 .2
28 - .
231
.236
- .2
39
.244
- .2
47
.252
- .2
55
20
VLSM AddressingCircle Method
Problem 13Using the network diagram and information given create an addressing
scheme which utilizes variable-length subnet masks. Show the subnetaddress and CIDR in the circle below, color or shade the sub-subnets used.This company will be using the class C address 200.150.70.0.Remember to start with your largest groups first.
New Delhi
LAN Address:
22 Hosts
5 Hosts
LAN Address:
LAN Address:
7 Hosts
LAN Address:
35 Hosts
Serial Address:
Mumbai
12HostsLAN Address:
Color in the necessary circle sections used with differentshades to highlight each subnet.
.0 -
.3
.24
- .27
.8 -
.11
.16
- .19
.64 - .67
.56 - .59
.48 - .51
.40 - .43.32
- .35
.104 - .107.96 - .99
.88 - .91
.80 - .83
.72 - .75
.112 - .115
.120 - .123
.176 - .179
.224 -
.227
.216 - .219
.192 - .195
.208 - .211
.200 - .203
.184 - .187
.168. - 171
.152 - .155
.136 - .139
.160 - .163 .144 - .147
.128 - .131
.248
- .2
51
.232
- .23
5
.240
- .2
43
.4 -
.7
.12
- .15
.20
- .23
.28 -
.31
.36 - .39
.44 - .47
.52 - .55
.60 - .63
.68 - .71
.76 - .79.84 - .87.92 - .95
.100 - .103
.108 - .111
.116 - .119
.124 - .127
.132 - .135
.140 - .143.148 - .151
.156 - .159
.164 - .167
.172. - 175
.180 - .183
.188 - .191
.196 - .199
.204 - .207.212 - .2
15 .220 -
.223 .2
28 - .
231
.236
- .2
39
.244
- .2
47
.252
- .2
55
21
VLSM AddressingCircle Method
Problem 14Using the network diagram and information given create an addressing
scheme which utilizes variable-length subnet masks. Show the subnetaddress and CIDR in the circle below, color or shade the sub-subnets used.This company will be using the class C address 210.10.10.0.Remember to start with your largest groups first.LAN Address:
Hong Kong
WAN Address #2:
18 Hosts
LAN Address:
95 Hosts 12 Hosts
LAN Address:
LAN Address:
27 Hosts
WAN Address #1:
Shanghai
Beijing
18 Hosts
Draw the necessary lines and color in the used circle sectionswith different shades to highlight each subnet.
.0
.127
.191
.128
.223
.192
.224 .31.32
.63
.64
.95
.96.159
.160
.255
22
VLSM AddressingCircle Method
Problem 15Using the network diagram and information given create an addressing
scheme which utilizes variable-length subnet masks. Show the subnetaddress and CIDR in the boxes below, color or shade the sub-subnets usedin the circle. This company will be using the class C address 192.168.150.0.Remember to start with your largest groups first.
Vienna15 Hosts
Frankfurt30 Hosts
LAN Address:
LAN Address:
WAN Address #2:
Prague
12 Hosts
48 Hosts
LAN Address:
WAN Address #1:
Draw the necessary lines andcolor in the used circle sectionswith different shades to highlighteach subnet.
Venice 23 Hosts
48 Hosts
LAN Address:
WAN Address #3:LAN Address:
.0
.127
.191
.128
.192 .63.64
.255
23
VLSM AddressingCircle Method
Problem 16Using the network diagram and information given create an addressing
scheme which utilizes variable-length subnet masks. Show the subnetaddress and CIDR in the boxes below, color or shade the sub-subnets usedin the circle. This company will be using the class C address 195.75.23.0.Remember to start with your largest groups first.
San Juan
LAN Address:
WAN Address #1:
Draw the necessary lines andcolor in the used circle sectionswith different shades to highlighteach subnet.
Kingston
WAN Address #2:
6 Hosts
12 Hosts
LAN Address:
24 Hosts 37 Hosts
LAN Address:
LAN Address:
Guatemala City
San Jose
12 Hosts
LAN Address:
13 Hosts
WAN Address #3
.0
.127.128
.255
Visualizing Subnets Using aVLSM Chart
The VLSM chart is the third method used to visualize the breakdown ofsubnets and addresses into smaller sizes. By shading or coloring in theboxes you can easily break up your subnets without overlapping youraddresses. You can adjust each sub-subnet to the correct size needed.
24
MarketingDepartment
60 Hosts
LAN Address:
220.10.10.0/26
ResearchDepartment
28 Hosts
LAN Address:
220.10.10.64/27
VLSM AddressingVLSM Chart Method
(Sample)
Problem 17Using the network diagram and information given create an addressing
scheme which utilizes variable-length subnet masks. Show the subnetaddress and CIDR in the boxes below, color or shade the sub-subnets used inthe chart. This business will be using the class C address 220.10.10.0. Re-member to start with your largest groups first.
Problem 18Using the network diagram and information given create an address-
ing scheme which utilizes variable-length subnet masks. Show the subnetaddress and CIDR in the boxes below, color or shade the sub-subnets used inthe chart. This company will be using the class C address 192.168.16.0. Re-member to start with your largest groups first.
Problem 19Using the network diagram and information given create an
addressing scheme which utilizes variable-length subnet masks. Show thesubnet address and CIDR in the boxes below, color or shade the sub-subnetsused in the chart. This company will be using the class C address 199.55.78.0.Remember to start with your largest groups first.
Problem 20Using the network diagram and information given create an
addressing scheme which utilizes variable-length subnet masks. Show thesubnet address and CIDR in the boxes below, color or shade the sub-subnetsused in the chart. This company will be using the class C address 223.150.50.0.Remember to start with your largest groups first.
Problem 21Using the network diagram and information given create an
addressing scheme which utilizes variable-length subnet masks. Show thesubnet address and CIDR in the boxes below, color or shade the sub-subnetsused in the chart. This company will be using the class C address 222.22.2.0.Remember to start with your largest groups first.
Problem 22Using the network diagram and information given create an
addressing scheme which utilizes variable-length subnet masks. Show thesubnet address and CIDR in the boxes below, color or shade the sub-subnetsused in the chart. This company will be using the class C address 200.20.2.0.Remember to start with your largest groups first.
Problem 23Using the network diagram and information given create an
addressing scheme which utilizes variable-length subnet masks. Show thesubnet address and CIDR in the boxes below, color or shade the sub-subnetsused in the chart. This company will be using the class C address 190.150.23.0.Remember to start with your largest groups first.
Problem 24Using the network diagram and information given create an
addressing scheme which utilizes variable-length subnet masks. Show thesubnet address and CIDR in the boxes below, color or shade the sub-subnetsused in the chart. This company will be using the class C address 192.168.1.0.Remember to start with your largest groups first.
Use the VLSM method of your choice to completethe folowing problems.
.0 -
.3
.24 -
.27
.8 -
.11
.16
- .19
.64 - .67
.56 - .59
.48 - .51
.40 - .43
.32 -
.35
.104 - .107.96 - .99
.88 - .91
.80 - .83
.72 - .75
.112 - .115
.120 - .123
.176 - .179
.224
- .22
7.216 - .2
19
.192 - .195
.208 - .211
.200 - .203
.184 - .187
.168. - 171
.152 - .155 .136 - .139
.160 - .163
.144 - .147
.128 - .131
.248
- .2
51
.232
- .2
35
.240
- .2
43 .4 -
.7
.12
- .15
.20
- .23
.28 -
.31
.36 - .39
.44 - .47
.52 - .55
.60 - .63
.68 - .71
.76 - .79
.84 - .87.92 - .95
.100 - .103
.108 - .111
.116 - .119
.124 - .127
.132 - .135
.140 - .143
.148 - .151.156 - .159
.164 - .167
.172. - 175
.180 - .183
.188 - .191
.196 - .199
.204 - .207.212 - .2
15.22
0 - .2
23 .228
- .23
1
.236
- .2
39
.244
- .2
47
.252
- .2
55
VL
SM
Ad
dre
ssin
g(S
ampl
e)
Pro
ble
m 2
5Yo
u ar
e de
velo
ping
a s
choo
l net
wor
k w
ith t
he c
lass
C a
ddre
ss 1
92.1
68.2
.0/2
4.
The
re w
ill b
e th
ree
com
pute
r la
bs w
ith 3
0 co
mpu
ters
eac
h th
at n
eed
to b
e on
diff
eren
t su
b-su
bnet
s.
For
ty e
ight
cla
ssro
oms
with
one
com
pute
r ea
ch t
hat
will
com
pris
e a
sing
le s
ub-s
ubne
t. T
he a
dmin
istr
ativ
e of
fice
and
guid
ance
offi
ceco
ntai
n a
tota
l of
seve
n co
mpu
ters
whi
ch w
ill n
eed
to b
e gr
oupe
d to
geth
er.
Pla
n fo
r fo
ur m
ore
min
i lab
s w
ithsi
x co
mpu
ters
to
each
sub
-sub
netw
ork.
D
ivid
e th
e ne
twor
k us
ing
varia
ble
leng
th s
ubne
t m
asks
. C
ompl
ete
the
info
rmat
ion
requ
ired
belo
w.
Rem
embe
r to
wor
k fr
om la
rges
t to
sm
alle
st.
Sub
net
1 2 3 4 5 6 7 8 9 10 11 12 13 14
Sub
net
Add
ress
192
.168
.2.0
192
.168
.2.6
419
2.1
68.2
.96
192
.168
.2.1
28
192
.168
.2.1
6019
2.1
68.2
.176
192
.168
.2.1
8419
2.1
68.2
.192
192
.168
.2.2
00
Sub
net
Mas
k (/
X)
/26
/27
/27
/27
/28
/29
/29
/29
/29
Firs
t Usa
ble
Hos
t19
2.1
68.2
.119
2.1
68.2
.65
192
.168
.2.9
719
2.1
68.2
.12
919
2.1
68.2
.161
192
.168
.2.1
7719
2.1
68.2
.185
192
.168
.2.1
9319
2.1
68.2
.201
Last
Usa
ble
Hos
t19
2.1
68.2
.62
192
.168
.2.9
419
2.1
68.2
.12
619
2.1
68.2
.15
819
2.1
68.2
.174
192
.168
.2.1
8219
2.1
68.2
.190
192
.168
.2.1
9819
2.1
68.2
.206
Bro
adca
stA
ddre
ss19
2.1
68.2
.63
192
.168
.2.9
519
2.1
68.2
.12
719
2.1
68.2
.15
919
2.1
68.2
.175
192
.168
.2.1
8319
2.1
68.2
.191
192
.168
.2.1
9919
2.1
68.2
.207
42
43
VL
SM
Ad
dre
ssin
g(S
ampl
e)
Pro
ble
m 2
6Yo
u ar
e se
tting
up
a sm
all b
usin
ess
netw
ork
with
the
cla
ss C
add
ress
220
.55.
80.0
/24.
T
he m
arke
ting
divi
sion
will
nee
d 12
com
pute
rs.
Res
earc
h an
d de
velo
pmen
t ne
eds
27 c
ompu
ters
. T
he r
ecep
tion
area
will
need
tw
o co
mpu
ters
. M
anag
emen
t re
quire
s 19
com
pute
rs.
Div
ide
the
netw
ork
usin
g va
riabl
e le
ngth
sub
net
mas
ks.
Com
plet
e th
e in
form
atio
n re
quire
d be
low
. R
emem
ber
to w
ork
from
larg
est
to s
mal
lest
.
Sub
net
1 2 3 4 5 6 7 8 9 10 11 12 13 14
Sub
net
Add
ress
22
0.5
5.8
0.0
22
0.5
5.8
0.32
22
0.5
5.8
0.64
22
0.5
5.8
0.80
Sub
net
Mas
k (/
X)
/27
/27
/28
/30
Firs
t Usa
ble
Hos
t2
20.
55
.80.
12
20.
55
.80.
22
0.5
5.8
0.65
22
0.5
5.8
0.81
Last
Usa
ble
Hos
t2
20.
55
.80.
302
20.
55
.80.
622
20.5
5.8
0.7
82
20.
55
.80.
82
Bro
adca
stA
ddre
ss2
20.
55
.80.
312
20.
55
.80.
632
20.
55
.80.
792
20.
55
.80.
83
44
VL
SM
Ad
dre
ssin
g
Pro
ble
m 2
7Yo
u ar
e se
tting
up
a m
ediu
m s
ized
net
wor
k w
ith t
he c
lass
C a
ddre
ss 2
22.3
7.34
.0/2
4.
Mar
ketin
g ne
eds
29 c
ompu
ters
. R
esea
rch
and
deve
lopm
ent
need
s 11
0 co
mpu
ters
. B
ookk
eepi
ng w
ill u
se 1
2 co
mpu
ters
.T
he r
ecep
tion
area
will
nee
d th
ree
com
pute
rs.
Man
agem
ent
requ
ires
60 c
ompu
ters
. D
ivid
e th
e ne
twor
kus
ing
varia
ble
leng
th s
ubne
t m
asks
. C
ompl
ete
the
info
rmat
ion
requ
ired
belo
w.
Rem
embe
r to
wor
k fr
omla
rges
t to
sm
alle
st.
Sub
net
1 2 3 4 5 6 7 8 9 10 11 12 13 14
Sub
net
Add
ress
Sub
net
Mas
k (/
X)
Firs
t Usa
ble
Hos
tLa
st U
sabl
eH
ost
Bro
adca
stA
ddre
ss
45
VL
SM
Ad
dre
ssin
g
Pro
ble
m 2
8A
shi
ppin
g co
mpa
ny n
eeds
to
set
up it
s ne
twor
k ac
ross
sev
eral
loca
tions
. T
he D
enve
r of
fice
need
s si
xco
mpu
ters
. T
he W
aco
offic
e ne
eds
22 c
ompu
ters
. T
he F
argo
offi
ce w
ill n
eed
five
com
pute
rs.
The
WA
Nlin
ks b
etw
een
all t
hree
loca
tions
nee
d to
be
incl
uded
in t
he s
olut
ion.
U
sing
the
IP
add
ress
192
.168
.10.
0/24
divi
de t
he n
etw
ork
usin
g V
LSM
. C
ompl
ete
the
info
rmat
ion
requ
ired
belo
w.
Rem
embe
r to
wor
k fr
om la
rges
tto
sm
alle
st.
Sub
net
1 2 3 4 5 6 7 8 9 10 11 12 13 14
Sub
net
Add
ress
Sub
net
Mas
k (/
X)
Firs
t Usa
ble
Hos
tLa
st U
sabl
eH
ost
Bro
adca
stA
ddre
ss
46
VL
SM
Ad
dre
ssin
g
Pro
ble
m 2
9A
new
sch
ool i
s be
ing
built
in th
e lo
cal s
choo
l dis
tric
t. It
will
hav
e th
ree
com
pute
r la
bs w
ith 2
8co
mpu
ters
eac
h.
The
re w
ill b
e 58
cla
ssro
oms
with
2 c
ompu
ters
eac
h th
at n
eed
to b
e on
one
sub
-sub
net.
The
offi
ce s
taff
and
adm
inis
trat
ors
will
nee
d 7
com
pute
rs.
The
gui
danc
e an
d at
tend
ance
offi
ce w
ill h
ave
5co
mpu
ters
. T
he s
choo
l ha
s be
en g
iven
the
add
ress
223
.145
.75.
0/24
. C
ompl
ete
the
info
rmat
ion
requ
ired
belo
w.
Rem
embe
r to
wor
k fr
om la
rges
t to
sm
alle
st.
Sub
net
1 2 3 4 5 6 7 8 9 10 11 12 13 14
Sub
net
Add
ress
Sub
net
Mas
k (/
X)
Firs
t Usa
ble
Hos
tLa
st U
sabl
eH
ost
Bro
adca
stA
ddre
ss
47
VL
SM
Ad
dre
ssin
g
Pro
ble
m 3
0A
loca
l col
lege
is s
ettin
g up
a c
ampu
s w
ide
netw
ork.
T
he te
chno
logy
win
g w
ill b
e on
its
own
netw
ork
addr
ess
of 1
92.1
68.2
50.0
/24.
T
he o
ffice
win
g w
ill in
clud
e 15
com
pute
rs.
The
re a
re 2
labs
of
20 c
ompu
ters
each
, 2
labs
of
30 c
ompu
ters
eac
h an
d on
e la
b of
35
com
pute
rs.
Com
plet
e th
e in
form
atio
n re
quire
d be
low
.R
emem
ber
to w
ork
from
larg
est
to s
mal
lest
.
Sub
net
1 2 3 4 5 6 7 8 9 10 11 12 13 14
Sub
net
Add
ress
Sub
net
Mas
k (/
X)
Firs
t Usa
ble
Hos
tLa
st U
sabl
eH
ost
Bro
adca
stA
ddre
ss
48
VL
SM
Ad
dre
ssin
g
Pro
ble
m 3
1Yo
u ar
e se
tting
up
a ne
twor
k fo
r a
com
pany
in f
our
loca
tions
. L
ocat
ion
A h
as 8
com
pute
rs.
Loc
atio
n B
has
122
com
pute
rs.
Loc
atio
n C
has
4 c
ompu
ters
. L
ocat
ion
D h
as 5
5 co
mpu
ters
. T
here
is a
WA
N c
onne
c-tio
n be
twee
n al
l fou
r lo
catio
ns.
Com
plet
e th
e in
form
atio
n re
quire
d be
low
usi
ng t
he c
lass
C a
ddre
ss19
2.16
8.10
.0.
Rem
embe
r to
wor
k fr
om l
arge
st t
o sm
alle
st.
Sub
net
1 2 3 4 5 6 7 8 9 10 11 12 13 14
Sub
net
Add
ress
Sub
net
Mas
k (/
X)
Firs
t Usa
ble
Hos
tLa
st U
sabl
eH
ost
Bro
adca
stA
ddre
ss
49
VL
SM
Ad
dre
ssin
g
Pro
ble
m 3
2A
col
lege
dor
mito
ry is
bei
ng r
emol
ded.
A
new
net
wor
k is
bei
ng in
stal
led.
T
here
are
50
dorm
roo
ms
with
tw
o dr
ops
each
tha
t w
ill b
e on
one
sub
-sub
net.
The
offi
ces
will
hav
e 5
drop
s.
The
rec
eptio
n de
sk w
illha
ve t
hree
dro
ps.
A s
mal
l stu
dy h
all w
ill in
clud
e 30
dro
ps.
Usi
ng t
he I
P a
ddre
ss 1
92.1
68.1
2.0/
24 c
ompl
ete
the
info
rmat
ion
requ
ired
belo
w u
sing
VLS
M.
Wor
k fr
om la
rges
t to
sm
alle
st.
Sub
net
1 2 3 4 5 6 7 8 9 10 11 12 13 14
Sub
net
Add
ress
Sub
net
Mas
k (/
X)
Firs
t Usa
ble
Hos
tLa
st U
sabl
eH
ost
Bro
adca
stA
ddre
ss
50
VL
SM
Ad
dre
ssin
g
Pro
ble
m 3
3Yo
u ar
e se
tting
up
a bu
sine
ss n
etw
ork
with
the
cla
ss C
add
ress
219
.75.
160.
0/24
. T
he m
arke
ting
divi
sion
will
nee
d 19
com
pute
rs.
Res
earc
h an
d de
velo
pmen
t ne
eds
40 c
ompu
ters
. T
he r
ecep
tion
area
will
need
fou
r co
mpu
ters
. M
anag
emen
t re
quire
s 12
com
pute
rs.
Div
ide
the
netw
ork
usin
g va
riabl
e le
ngth
sub
net
info
rmat
ion.
O
n th
e op
posi
te p
age
draw
a d
etai
led
map
of
this
net
wor
k.
Incl
ude
the
nam
e an
d su
b-su
bnet
IP
addr
esse
s fo
r ea
ch b
ranc
h of
the
netw
ork
with
the
subn
et m
ask.
O
ne r
oute
r w
ith fo
ur e
ther
net p
orts
will
be
used
for
thi
s ne
twor
k.
Sub
net
1 2 3 4 5 6 7 8 9 10 11 12 13 14
Sub
net
Add
ress
Sub
net
Mas
k (/
X)
Firs
t Usa
ble
Hos
tLa
st U
sabl
eH
ost
Bro
adca
stA
ddre
ss
51
Pro
ble
m 3
3 -
Det
aile
d M
apD
raw
a d
etai
led
map
of
this
net
wor
k.
Incl
ude
the
nam
e an
d su
b-su
bnet
IP
add
ress
esin
form
atio
n fo
r ea
chbr
anch
of t
he n
etw
ork,
and
the
subn
et m
ask.
52
VL
SM
Ad
dre
ssin
g
Pro
ble
m 3
4A
sm
all c
ompa
ny n
eeds
to
set
up it
s ne
twor
k ac
ross
sev
eral
loca
tions
. T
he N
ew Y
ork
bran
ch o
ffice
need
s 15
com
pute
rs.
The
San
Jos
e of
fice
need
s 66
com
pute
rs.
The
Trin
idad
offi
ce w
ill n
eed
18co
mpu
ters
. Y
ou w
ill n
eed
two
WA
N li
nks
betw
een
the
rout
ers.
U
sing
the
IP
add
ress
195
.20.
5.0/
24 d
ivid
e th
ene
twor
k us
ing
VLS
M.
On
the
oppo
site
pag
e dr
aw a
det
aile
d m
ap o
f th
is n
etw
ork.
In
clud
e th
e na
me
and
sub-
subn
et I
P a
ddre
sses
info
rmat
ion
for
each
bra
nch
of t
he n
etw
ork.
La
bel t
he W
AN
link
s w
ith t
he s
ame
info
rma-
tion.
C
ompl
ete
the
info
rmat
ion
requ
ired
belo
w.
Wor
k fr
om la
rges
t to
sm
alle
st.
Sub
net
1 2 3 4 5 6 7 8 9 10 11 12 13 14
Sub
net
Sub
net
Mas
k (/
X)
Firs
t Usa
ble
Hos
tLa
st U
sabl
eH
ost
Bro
adca
stA
ddre
ss
Pro
ble
m 3
4 -
Det
aile
d M
apD
raw
a d
etai
led
map
of
this
net
wor
k.
Incl
ude
the
nam
eand
sub
-sub
net
IP a
ddre
sses
info
rmat
ion
for
each
bran
ch o
f the
net
wor
k.
53
54
Class A and B
VLSMProblems
Class A AddressesVLSM Chart 8-15 Bits (2nd octet)
Class B AddressesVLSM Chart 16-23 Bits (3rd octet)
Class C AddressesVLSM Chart 24-30 Bits (4th octet)
10 . 0 . 0 . 0
VLSMwith
Class A and B Addresses
We’ve gone over the practical applications of using VLSM on class C addresses. The sameapproach works with class A and B addresses. For example an ISP may have a class Aaddress which it needs to subnet between its customers. Each customer may need to taketheir addresses and subnet them again in order to use them more effectively. The real trick tothis is to remember which octet of the IP address you are working with.
Sample Problem 35Part 1 of 3
Use the Class A address chart to break down the address for different ISP customers. At this
stage of the problem you are creating subnets using the second octet of the IP address.
Customer #5 has a total of 524,288 addresses. Use the Class B address chart to breakdown the sub-subnetwork addresses for their different clients. At this stage of the problem youare creating sub-subnets with the third octet of the IP address.
Client #8 has a total of 1,024 addresses. Use the Class C address chart to break down thesub-subnetwork addresses for their different branch offices. At this stage of the problem youare creating sub-subnets with the fourth octet of the IP address.
The school system you are working for is using the private address of 172.32.0.0 to subnet theentire district. Use the Class B address chart to break down the sub-subnetwork addressesfor the different schools and offices.
At this stage of the problem you are creating sub-subnets with the third octet of the IP address.Remember which octet of the IP address you are working in.
Eastern Elementary has been given 512 hosts, with the address range of 172.32.42.0 / 21(255.255.248.0).
Based on the information below supply the required address ranges and subnet masks foreach school area. Use the Class C address chart to break down the sub-subnetworks.
Hint: Another way to look at this problem is to see that with the third octet range of 42 to 43 youhave access to 2 groups of 255 addresses (172.32.42.0 and 172.32.43.0). Think in terms ofhaving two Class C VLSM charts.
Eastern Elementary SchoolAddress Range 172.32.42.0 to 172.32.43.255
South High in part 1 of this problem has been given 2,048 hosts, with the address range of172.32.16.0 / 21 (255.255.248.0).
Based on the information below supply the required address ranges and subnet masks foreach school area. Use both the Class B and Class C address charts to break down the sub-subnetwork addresses for the different areas of the network.
Hint:With this problem you are creating sub-subnets with both the third and fourth octets of the IPaddress. You may need to use the Class B VLSM chart for the Students addressinginformation. All the other addresses will be using the Class C VLSM chart. Another way tolook at this problem is to see that with the third octect range of 16 to 23 you have access to 8groups of 255 addresses or eight Class C VLSM charts.
South High SchoolAddress Range 172.32.16.0 to 172.32.23.255
The company you are working for is using the IP address 110.0.0.0 sub-subneted for multipleoffices around the world. Use the Class A address chart to break down the sub-subnetworkaddresses for the different offices.
At this stage of the problem you are creating sub-subnets with the third octet of the IP address.Remember which octet of the IP address you are working in.
London in part 1 of this problem has been given 1,048,576 hosts, with the address range of110.128.0.0 to 110.143.255.255 /12 (255.240.0.0).
Based on the information below supply the required address ranges and subnet masks foreach office. Use the Class B address chart to break down the sub-subnetwork addresses forthe different areas of the network.
LondonAddress Range 110.128.0.0 to 110.143.255.255
Office #7 in part 2 of this problem has been given 512 hosts, with the address range of110.128.80.0 / 23 (255.255.254.0).
Based on the information below supply the required address ranges and subnet masks foreach school area. Use the Class C address chart to break down the sub-subnetworkaddresses for the different areas of the network. Hint: Another way to look at this problem isto see that with the third octect range of 80 to 81 you have access to 2 groups of 255addresses or two Class C VLSM charts.
Office #7Address Range 110.128.80.0 to 110.128.81.255
Use the Class A address chart to break down the address for different business customers bycountry. At this stage of this problem you are creating subnets in the second octet of the IPaddress.
The United States customers have a total of 8,388,608 addresses. Use the Class A addresschart to break down the sub-subnetwork addresses for their different areas. At this stage ofthis problem you are creating sub-subnets in the second octet of the IP address.
Client #7 has a total of 524,288 addresses. Use the Class B address chart to break down thesub-subnetwork addresses for their different clients. At this stage of this problem you arecreating sub-subnets in the third or forth octet of the IP address.
Hint: Another way to look at this problem is to see that with the second octect range of 104 to111 you have access to 8 groups of 65,536 addresses or 8 Class B VLSM charts.
Office #7 from part 3 of 4 has a total of 8,192 addresses. Use the Class B address chart tobreak down the sub-subnetwork addresses for the different branch offices. At this stage of thisproblem you are creating sub-subnets in the third octet of the IP address.
Hint: Remember that the range of this problem is between 128 and 159 in the third octect.
Your subnetting will start in the middle of the chart not at the top for this range.