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Online subscription help
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Help
on IP addresses
Every computer connected to the internet has an IP address. Like a postal
code (or zip code), this IP address identifies the location of the computer
so that information can be sent to and from it.
An IP address consists of four numbers, separated by
dots ('.').
IP addresses are grouped into IP networks. Here are
three types of IP networks:
- Class 'A' networks contain several millions of computers. The first
number of the IP addresses of all these computers is the same. Very
few organisations are large enough to merit a class 'A' network.
Class 'A' networks begin with a number in the range of 1 to 126.
- Class 'B' networks contain several thousands of computers. All these
computers share the same numbers in the first two positions of their
IP addresses. Many universities own one or more class 'B' networks.
Class 'B' networks begin with a number in the range of 1 to 191.
- Class 'C' networks contain several hundreds of computers. All these
computers share the same numbers in the first three positions of their
addresses. Many small organisations own one or more class 'C' networks.
It is also common practice to split a class 'B' network into many class
'C' networks – this is called 'subnetting'.
Class 'C' networks begin with a number in the range of 1 to 224.
For example:
18.245.33.1 and 18.128.176.4 are both
in the class 'A' network 18.*.*.*
145.65.134.6 and 145.65.98.204 are both in the class 'B'
network 145.65.*.*
196.72.8.144 and 196.72.8.13 are both in the class 'C' network
196.72.8.*
We control institutional subscriptions by checking the
IP addresses of the computers accessing our site. You need to inform us
of the IP networks you would like covered under your institutional online
subscription, separately identifying proxy servers.
Please only register IP addresses of computers that
are used by persons or departments served by your library.
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