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Discovering computer networks: hands on in the Open Networking Lab
Discovering computer networks: hands on in the Open Networking Lab

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11.2 Routers and IP addresses

You’ve learned about IP addressing and subnet masks in earlier sessions. This section serves as a brief reminder of your earlier work and provides an opportunity to practise and test your understanding of subnetting.

Watch the video below, which is about 1.5 minutes long.

Routers and IP addresses

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Activity 3 Test yourself

5 minutes

1. How many IP addresses can be assigned to hosts on a subnet with a subnet mask of 255.255.255.240?

a. 

13


b. 

14


c. 

15


d. 

16


The correct answer is b.

Answer

Addresses with a subnet mask of 255.255.255.240 will run from XXX.XXX.XXX.240 to XXX.XXX.XXX.255. This provides 16 possible addresses. The lowest of these (XXX.XXX.XXX.240) will be assigned to the network address and the highest (XXX.XXX.XXX.255) is the broadcast address, leaving 14 addresses for the hosts.

2. Which of the following correctly describes the IP address 192.168.2.32/27?

a. 

It is a subnet network address.


b. 

It is a subnet host address.


c. 

It is a subnet broadcast address.


The correct answer is a.

Answer

With a subnet mask of /27 the last five bits are the host part. The binary equivalent of 32 is 100000 so this subnet has the addresses from 192.168.2.32 to 192.168.2.63. Therefore 192.168.2.32, being the lowest address, is the network address of this subnet.