AQA Computer Science A Level
Using Private IP AddressingBy Admin - June 21, 2020, 4:55 p.m.
Last Edit - June 24, 2020, 1:41 p.m.
IPv4 has many obvious limitations, but its 32bit nature is the main one. This severely limits the number of addresses available, but this was thought about many years ago and to combat this Public and Private IP ranges were set
Private IP addresses are used internally only, each device connected to the network will get a private IP address. A network will have a public IP to access the internet and externally. Private IP's will not route to any public address. Every IP address not in the private ranges are therefore public.
The private IP ranges are:
10.0.0.0to10.255.255.255(16 Million host ID's)172.16.0.0to172.31.255.255(Almost 1 Million host ID's)192.168.0.0to192.168.255.255(65,000 host ID's)
The benefits of this are:
- Frees up IP addresses
- Hides a network device from the internet
- Entire network can exist behind 1 public IP
- Internal networks can be extremely large
How is this used
The public IP address for my network is 82.7.198.16, this is the only public IP for my network and it connects to the router. My router also has a private IP of 192.168.0.1, a private IP is given to every device connected to my network. The Network ID is 192.168.0 and the Host ID is 1.
I'm writing this on my phone from 192.168.0.42, this blogging platform is hosted on a raspberry pi with the IP 192.168.0.56. I have many other devices connected but they all use the same Network ID and a different Host ID.
The key to this is Network Address Translation, this is the process of swapping the Private IP of the sending device to the Public IP of the router on the outward journey (The router will record all translations). Then on the inward journey the Public IP of the router is swapped to the Private IP of the sending device. It will know this by checking the translations record for the outward journey.
What can you do?
- login to your router and check out the connected devices
- look at the network settings of your PC and look for the IP address
- look on your mobile device, normally settings,about device, and then status
- check your public IP by searching 'whats my ip' in google