How do you determine the network class of an IP address? For example, I have the IP address 127.0.0.1
Network classes are deprecated. As a attempt to cope with IP address exhaustion, the concept of network classes has been dropped in 1992. Before that, for a company with a need for 300 IP addresses, a class C network with 255 addresses would not suffice and it therefore received a class B address space with 65535 addresses, thus wasting 65535-300=65235 addresses.
See the Wikipedia article on network classes for further info.
Class Ranges: First octet ----------------------------- Class A 1 - 127 Class B 128 - 191 Class C 192 - 223 -----------------------------
Though 127.0.0.1 is class A, it's reserved for loopback/testing.
The following are the classes of IP addresses.
Class A The first octet denotes the network address, and the last three octets are the host portion.Any IP address whose first octet is between 1 and 126 is a Class A address. Note that 0 is reserved as a part of the default address, and 127 is reserved for internal loopback testing.
Class B The first two octets denote the network address, and the last two octets are the host portion.Any address whose first octet is in the range 128 to 191 is a Class B address.
Class C The first three octets denote the network address, and the last octet is the host portion. The first octet range of 192 to 223 is a Class C address.
Class D Used for multicast. Multicast IP addresses have their first octets in the range 224 to 239.
Class E Reserved for future use and includes the range of addresses with a first octet from 240 to 255