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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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2.4 Public and private addresses

There are two major types of IP address: private addresses and public addresses. This part looks at the differences between these two types of address, and the different ways they are used.

Now watch the video below, which is about 6 minutes long.

Public and private IP addresses

Download this video clip.Video player: 14_public_and_private_ip_addresses.mp4
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Now try to answer the questions below.

Activity 4 Test yourself

15 minutes

These questions are about network addresses.

  • 1. On a private network, two devices have these IP addresses: 192.168.3.2 and 192.168.3.1. Could these be expected to work?

  • Yes, both these IP addresses would work.

  • 2. A data packet with a destination address of 172.16.25.16 is launched on to the public internet. Could it be expected to reach its destination?

  • No. This is a private network address.

  • 3. If someone setting up their home network were advised to give the gateway an address of 192.168.4.255, would this be good advice? If it is bad advice, suggest some good advice.

  • No. This is a broadcast address and cannot be allocated to a device. 192.168.4.254 would be suitable.

  • 4. If someone setting up their home network were advised to give the gateway an address of 192.168.1.284, would this be good advice? If it is bad advice, suggest some good advice.

  • No. 284 exceeds the largest possible number as part of an IP address. The largest possible number is 255, but that can’t be used as it’s a broadcast address. Better advice would be to use 192.168.1.254 or 192.168.1.1.