Address pool

An address pool is a set of Internet Protocol addresses assigned by IANA or an organisation tied to it.

These address pools are assigned primarily in three classes, enumerated A, B and C. A class A network is actually never assigned in practice; there are only 254 such usable networks containing 2563−2 available client IP addresses. Class B is somewhat smaller, having 65534 networks and the same amount of hosts. This is suitable for larger entities. Class C address pools are the most common and allow for 254 servers. 2563−2 class C networks could be assigned. Note that only one network is assigned, so that if an entity was assigned a class C address, they would be able to host 254 clients on one network. The other 2563 or so prefixes would not be usable by them.

An additional two classes, D and E, have been assigned by IANA for experimental use .

It is important to note that because of IP routing and NAT, each IP address can be used more than once.