Subnetting Question

Petej

Hi All, this is my first post as I have only just joined. I am currently studying for my network plus and am just starting to get to grips with subnetting. I have been practising using Class C addresses and thought all was going well until I tried with Class A and Class B. The problem I have (and I am sure it is pretty basic, but I am struggling a little) is once an octet gets to 255 is the next step 1 or 0 and how does it effect the previous octet? For example If I have a class B IP address of 172.24.140.254, how would this increment one step at a time? Would the next step be 172.24.140.255, or 172.24.141.0 or 172.24.141.1. I am guessing the three of those suggestions are incorrect. If somebody could give me the next three or four steps from 172.24.140.254 it would clear it up for me. Thanks in advance, and sorry if it is a basic question. Pete

NetworkVeteran

Petej wrote: »

If I have a class B IP address of 172.24.140.254, how would this increment one step at a time? Would the next step be 172.24.140.255, or 172.24.141.0 or 172.24.141.1.

172.24.140.254 => 172.24.140.255 => 172.24.141.0 => 172.24.141.1 OR

200.1.1.254 => 200.1.1.255 => 200.1.2.0 => 200.1.2.1

How an IPv4 address is incremented by one actually does not depend on what class the address is. It's like integer addition, except you "carry" when a digit is above 255, rather than when a digit is above 9.

Petej

Thanks! Sorry it was a basic question, but you answered it perfectly. Much appreciated! Pete