Special IPv4 Addresses
During assignment of IP addresses to host on a network, there are certain addresses that cannot be assigned to hosts; they are the Network Address and Broadcast Address.
Network and Broadcast Addresses
When assigning an address to a host, the first and last addresses are not to be assigned. The first address is the Network Address and last is reserved as the Broadcast Address.
e.g.
Given the Network 192.168.1.0 /24
192.168.1.0 (Network)
192.168.1.1 (default gateway)
192.168.1.255 (Broadcast)
So, 192.168.1.2 – 254 (hosts)
Default Route
The default route is used as all-purpose address in a network when a more specific route is available for packet routing.
e.g. 0.0.0.0 /8
Loopback
The loopback is a special address that all host in a network use to direct traffic to themselves. TCP/IP applications and services that operate in a device use this as a shortcut for communicating with one other. You can also ping the loopback address to test the configuration of TCP/IP on the local host.
Loopback address: 127.0.0.1
Link-Local Addresses
IPv4 addresses in the address block 169.254.0.0 to 169.254.255.255 (169.254.0.0 /16) are designated as link-local addresses. These addresses can be automatically assigned to the local host by the operating system in environments where no IP configuration is available. Only devices in the same network can use these address range.
TEST-NET Addresses.
The addresses 192.0.2.0 to 192.0.2.255 (192.0.2.0 /24) is set aside for teaching and learning purposes. These addresses can be used in documentation and network examples. Unlike the experimental addresses, network devices used in teaching and learning will accept these addresses in their configurations. You may often find these addresses used with the domain names example.com or example.net in RFCs, vendor, and protocol documentation.
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