how to assign ip address for more than 255 users in class C

Solution
You have to use supernetting (Classless Inter-Domain Routing). HERE is a calculator that makes it quite simple to determine your addresses for your specific client address numerical needs and address ranges. For example select 510 maximum addresses and use a starting IP address of 192.168.0.1, the calculator will provide a /23 address range for 512 addresses (two are not available for attaching client devices, the gateway and broadcast addresses).

RealBeast

Titan
Moderator
You have to use supernetting (Classless Inter-Domain Routing). HERE is a calculator that makes it quite simple to determine your addresses for your specific client address numerical needs and address ranges. For example select 510 maximum addresses and use a starting IP address of 192.168.0.1, the calculator will provide a /23 address range for 512 addresses (two are not available for attaching client devices, the gateway and broadcast addresses).
 
Solution