Information Technology Reference
In-Depth Information
Class E Addresses
Class E addresses range from 240 (11110000) to 254 (11111110) in the first byte. These
addresses are reserved for experimental networks. Network 255 is reserved for the broad-
cast address, such as 255.255.255.255. Table 8-10 summarizes the IPv4 address classes.
Again, each address class can be uniquely identified in binary by the high-order bits.
Ta b l e 8 -1 0
IPv4 Address Classes
Address Class
High-Order Bits
Network Numbers
A
0xxxxxxx
1.0.0.0 to 126.0.0.0
*
B
10xxxxxx
128.0.0.0 to 191.255.0.0
C
110xxxxx
192.0.0.0 to 223.255.255.0
D
1110xxxx
224.0.0.1 to 239.255.255.255
E
1111xxxx
240.0.0.0 to 254.255.255.255
*
Networks 0.0.0.0 and 127.0.0.0 are reserved as special-use addresses.
IPv4 Address Types
IPv4 addresses can also be classified in one of three types:
Unicast
■
Key
To p i c
Broadcast
■
Multicast
■
Unicast address represent a single interface of a host (PC, router, server). It can be a source
or destination IP address. A broadcast address is a destination IP address that is set to all
other devices in a given address range, normally it is sent to all devices in the IP subnet. A
multicast address is a destination IP address sent to a specific set of hosts. Table 8-11 sum-
marizes IPv4 address types.
Ta b l e 8 -1 1
IPv4 Address Type
Description
IPv4 Address
Type
The IP address of an interface on a single host. It can be a source or
destination address
Unicast
An IP address that reaches all hosts in an address range. It is only a
destination address.
Broadcast
An IP address that reaches a group of hosts. It is only a destination
address
Multicast
