If IP address of 192.168.1.3 and Default Gateway of 255.255.255.0 is given to a company , What is network and host address?

Dear Friend

I guess that the gateway IP is192.168.1.3 and the subnet mask is255.255.255.0

192.168.1.1 -192.168.1.254 are the IPs that you can use in your class C network (naturally the  IP192.168.1.3 is reserved to the gateway) and the Broadcast Address is192.168.1.255

Nowadays any modern OS can automatic calculate this but for more details and ways to setup a private network try a subnet calculator like:

http://www.subnet-calculator.com

It's very useful especially when we need to setup a firewall to protect a local network with some shared resources like file / mail / DNS server or printers / photocopy and so on.

Sometimes living open the access for local user and close it to the Net can be more easy if you  have all the data, e.g.: Mask Bits.

There also some exceptions to the general rule but are quite more like tricks for network architects that real work situations.

Regards

Renzo