IP Address Blocks

IP address assigned by ISP(Internet service Provider) is of static.

But changes when moved from one ISP location to another.

If you want to keep your IP address from one ISP to another, then go for IP blocks.

IP address blocks are block of IP addresses assigned from your Regional Internet Registry.

When there are redundant connections to internet via ISPs, then need to have range of IP addresses.

Size of 'block' assigned is written after an oblique(/) called "slash notation", which shows number of IP addresses contained in that block.

For example, in xx.xx.x.x/26, Ip addresses are 2⁸ (32-26=8) = 64.

IPv4 address space is assigned to end-user organizations for running internal networks but not for sub-delegation i.e., cannot let anyone else use IP addresses assigned for us.