Default Gateway and APIPA

Default Gateway:

All the PC’s connected with in the Network is communicated with other network devices by using this Default-Gateway only

Note: 127.0.0.0 – Loop back address

It is used for troubleshooting TCP/IP Stack. Self-check weather TCP/IP is working or installed properly.

APIPA – Automatic Private IP Address Assigning

With APIPA, DHCP clients can automatically self-configure an IP address and subnet mask when a DHCP server isn't available. When a DHCP client boots up, it first looks for a DHCP server in order to obtain an IP address and subnet mask.

APIPA allocates IP addresses in the private range 169.254.0.1 to 169.254.255.254. Clients verify their address is unique on the network using ARP. When the DHCP server is again able to service requests, clients update their addresses automatically.

In APIPA, all devices use the default network mask 255.255.0.0 and all reside on the same subnet.