Chapter 4: Easy Subnetting

255.192.0.0

/10

255.224.0.0

/11

255.240.0.0

/12

255.248.0.0

/13

255.255.252.0

/22

A, 15/9, 32768, 510

10.25.66.154/23 Address Class ? Number of Subnet and Host Bits? Number of Subnets (2x)? Number of Hosts (2x - 2)?

a

11. You have an interface on a router with the IP address of 192.168.192.10/29. What is the broadcast address the hosts will use on this LAN? A. 192.168.192.15 B. 192.168.192.31 C. 192.168.192.63 D. 192.168.192.127 E. 192.168.192.255

255.255.255.240, 14

/28 Subnet mask _____ Number of Hosts per Subnet (2x - 2) _____

255.255.255.248

/29

255.255.255.248, 6

/29 Subnet mask _____ Number of Hosts per Subnet (2x - 2) _____

255.255.255.252

/30

255.255.255.252, 2

/30 Subnet mask _____ Number of Hosts per Subnet (2x - 2) _____

255.0.0.0

/8

255.128.0.0

/9

1. 192.168.100.25/30. A /30 is 255.255.255.252. The valid subnet is 192.168.100.24, broadcast is 192.168.100.27, and valid hosts are 192.168.100.25 and 26.

1. 192.168.100.25/30

d

1. What is the maximum number of IP addresses that can be assigned to hosts on a local subnet that uses the 255.255.255.224 subnet mask? A. 14 B. 15 C. 16 D. 30 E. 31 F. 62

10. A /23 is 255.255.254.0. The third octet is a block size of 2. 0, 2, 4. The subnet is in the 16.2.0 subnet; the broadcast address is 16.3.255.

10. What is the subnet for host ID 10.16.3.65/23?

C, 4/4, 16, 14

192.168.20.123/28 Address Class ? Number of Subnet and Host Bits? Number of Subnets (2x)? Number of Hosts (2x - 2)?

2

2 to the power of 1

1024

2 to the power of 10

2048

2 to the power of 11

4096

2 to the power of 12

8192

2 to the power of 13

16384

2 to the power of 14

4

2 to the power of 2

8

2 to the power of 3

16

2 to the power of 4

32

2 to the power of 5

64

2 to the power of 6

128

2 to the power of 7

256

2 to the power of 8

512

2 to the power of 9

2. 192.168.100.37/28. A /28 is 255.255.255.240. The fourth octet is a block size of 16. Just count by 16s until you pass 37. 0, 16, 32, 48. The host is in the 32 subnet, with a broadcast address of 47. Valid hosts 33-46.

2. 192.168.100.37/28

d

2. You have a network that needs 29 subnets while maximizing the number of host addresses available on each subnet. How many bits must you borrow from the host field to provide the correct subnet mask? A. 2 B. 3 C. 4 D. 5 E. 6 F. 7

a

20. Given an IP address 172.16.28.252 with a subnet mask of 255.255.240.0, what is the correct network address? A. 172.16.16.0 B. 172.16.0.0 C. 172.16.24.0 D. 172.16.28.0

C, 6/2, 64, 2

208.100.54.209/30 Address Class ? Number of Subnet and Host Bits? Number of Subnets (2x)? Number of Hosts (2x - 2)?

f

4. The network address of 172.16.0.0/19 provides how many subnets and hosts? A. 7 subnets, 30 hosts each B. 7 subnets, 2,046 hosts each C. 7 subnets, 8,190 hosts each D. 8 subnets, 30 hosts each E. 8 subnets, 2,046 hosts each F. 8 subnets, 8,190 hosts each

5. 192.168.100.99/26. A /26 is 255.255.255.192. The fourth octet has a block size of 64. 0, 64, 128. The host is in the 64 subnet, broadcast of 127. Valid hosts 65-126.

5. 192.168.100.99/26

b, d

5. Which two statements describe the IP address 10.16.3.65/23? (Choose two.) A. The subnet address is 10.16.3.0 255.255.254.0. B. The lowest host address in the subnet is 10.16.2.1 255.255.254.0. C. The last valid host address in the subnet is 10.16.2.254 255.255.254.0. D. The broadcast address of the subnet is 10.16.3.255 255.255.254.0. E. The network is not subnetted.

6. 192.168.100.99/25. A /25 is 255.255.255.128. The fourth octet is a block size of 128. 0, 128. The host is in the 0 subnet, broadcast of 127. Valid hosts 1-126.

6. 192.168.100.99/25

d

6. If a host on a network has the address 172.16.45.14/30, what is the subnetwork this host belongs to? A. 172.16.45.0 B. 172.16.45.4 C. 172.16.45.8 D. 172.16.45.12 E. 172.16.45.16

A, 10/14, 1024, 16382

63.24.89.21/18 Address Class ? Number of Subnet and Host Bits? Number of Subnets (2x)? Number of Hosts (2x - 2)?

d

7. Which mask should you use on point-to-point links in order to reduce the waste of IP addresses? A. /27 B. /28 C. /29 D. /30 E. /31

7. A default Class B is 255.255.0.0. A Class B 255.255.255.0 mask is 256 subnets, each with 254 hosts. We need fewer subnets. If we used 255.255.240.0, this provides 16 subnets. Let's add one more subnet bit. 255.255.248.0. This is 5 bits of subnetting, which provides 32 subnets. This is our best answer, a /21.

7. You have a Class B network and need 29 subnets. What is your mask?

8. A /29 is 255.255.255.248. This is a block size of 8 in the fourth octet. 0, 8, 16. The host is in the 8 subnet, broadcast is 15.

8. What is the broadcast address of 192.168.192.10/29?

c

8. What is the subnetwork number of a host with an IP address of 172.16.66.0/21? A. 172.16.36.0 B. 172.16.48.0 C. 172.16.64.0 D. 172.16.0.0

9. A /29 is 255.255.255.248, which is 5 subnet bits and 3 host bits. This is only 6 hosts per subnet.

9. How many hosts are available with a Class C /29 mask?

a

9. You have an interface on a router with the IP address of 192.168.192.10/29. Including the router interface, how many hosts can have IP addresses on the LAN attached to the router interface? A. 6 B. 8 C. 30 D. 62 E. 126

255.255.255.192

/26

255.255.255.192, 62

/26 Subnet mask _____ Number of Hosts per Subnet (2x - 2) _____

255.255.255.224

/27

255.255.255.224, 30

/27 Subnet mask _____ Number of Hosts per Subnet (2x - 2) _____

255.255.255.240

/28

255.255.248.0

/21

255.255.248.0, 2046

/21 Subnet mask _____ Number of Hosts per Subnet (2x - 2) _____

255.255.252.0, 1022

/22 Subnet mask _____ Number of Hosts per Subnet (2x - 2) _____

255.255.254.0

/23

255.255.254.0, 510

/23 Subnet mask _____ Number of Hosts per Subnet (2x - 2) _____

255.255.255.0

/24

255.255.255.0, 254

/24 Subnet mask _____ Number of Hosts per Subnet (2x - 2) _____

255.255.255.128

/25

255.255.255.128, 126

/25 Subnet mask _____ Number of Hosts per Subnet (2x - 2) _____

255.252.0.0

/14

255.254.0.0

/15

255.255.0.0

/16

255.255.0.0, 65534

/16 Subnet mask _____ Number of Hosts per Subnet (2x - 2) _____

255.255.128.0

/17

255.255.128.0, 32766

/17 Subnet mask _____ Number of Hosts per Subnet (2x - 2) _____

255.255.192.0

/18

255.255.192.0, 16382

/18 Subnet mask _____ Number of Hosts per Subnet (2x - 2) _____

255.255.224.0

/19

255.255.224.0, 8190

/19 Subnet mask _____ Number of Hosts per Subnet (2x - 2) _____

255.255.240.0

/20

255.255.240.0, 4094

/20 Subnet mask _____ Number of Hosts per Subnet (2x - 2) _____

c

10. You need to configure a server that is on the subnet 192.168.19.24/29. The router has the first available host address. Which of the following should you assign to the server? A. 192.168.19.0 255.255.255.0 B. 192.168.19.33 255.255.255.240 C. 192.168.19.26 255.255.255.248 D. 192.168.19.31 255.255.255.248 E. 192.168.19.34 255.255.255.240

b

12. You need to subnet a network that has 5 subnets, each with at least 16 hosts. Which classful subnet mask would you use? A. 255.255.255.192 B. 255.255.255.224 C. 255.255.255.240 D. 255.255.255.248

B, 4/12, 16, 4094

128.1.1.254/20 Address Class ? Number of Subnet and Host Bits? Number of Subnets (2x)? Number of Hosts (2x - 2)?

c

13. You configure a router interface with the IP address 192.168.10.62 255.255.255.192 and receive the following error: Bad mask /26 for address 192.168.10.62 A. Why did you receive this error? B. You typed this mask on a WAN link and that is not allowed. C. This is not a valid host and subnet mask combination. D. ip subnet-zero is not enabled on the router. E. The router does not support IP.

a

14. If an Ethernet port on a router were assigned an IP address of 172.16.112.1/25, what would be the valid subnet address of this interface? A. 172.16.112.0 B. 172.16.0.0 C. 172.16.96.0 D. 172.16.255.0 E. 172.16.128.0

b

17. You have a network in your data center that needs 310 hosts. Which mask should you use so you waste the least amount of addresses? A. 255.255.255.0 B. 255.255.254.0 C. 255.255.252.0 D. 255.255.248.0

B, 8/8, 256, 254

172.31.254.12/24 Address Class ? Number of Subnet and Host Bits? Number of Subnets (2x)? Number of Hosts (2x - 2)?

e

18. You have a network with a host address of 172.16.17.0/22. From the following options, which is another valid host address in the same subnet? A. 172.16.17.1 255.255.255.252 B. 172.16.0.1 255.255.240.0 C. 172.16.20.1 255.255.254.0 D. 172.16.16.1 255.255.255.240 E. 172.16.18.255 255.255.252.0 F. 172.16.0.1 255.255.255.0

d, e

19. Your router has the following IP address on Ethernet0: 172.16.2.1/23. Which of the following can be valid host IDs on the LAN interface attached to the router? (Choose two.) A. 172.16.0.5 B. 172.16.1.100 C. 172.16.1.198 D. 172.16.2.255 E. 172.16.3.0 F. 172.16.3.255

3. A /27 is 255.255.255.224. The fourth octet is a block size of 32. Count by 32s until you pass the host address of 66. 0, 32, 64, 96. The host is in the 64 subnet, and the broadcast address is 95. Valid host range is 65-94.

3. 192.168.100.66/27

c

3. What is the subnetwork address for a host with the IP address 200.10.5.68/28? A. 200.10.5.56 B. 200.10.5.32 C. 200.10.5.64 D. 200.10.5.0

4. 192.168.100.17/29. A /29 is 255.255.255.248. The fourth octet is a block size of 8. 0, 8, 16, 24. The host is in the 16 subnet, broadcast of 23. Valid hosts 17-22.

4. 192.168.100.17/29

ip subnet-zero

This command allows you to use the first and last subnet in your network design.