Super User is a question and answer site for computer enthusiasts and power users. It's 100% free, no registration required.

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

I've been served with a question to find Major Network Mask and I've only given Host IP address and sub-net mask. I have to find the Major Network Mask using Host IP and sub-net mask.

Another stackoverflow question says both are the same

I've attached screenshots of the question and the steps.

The step describes how to filter host and network information, but you need to find Major Network mask to draw M.D. line.

Step describing drawing M.D line

but in my question, I've only given Host IP and subnet mask. enter image description here

share|improve this question
I suspect this is classful addressing, so the major network mask would be for 10.x.x.x. – David Schwartz Sep 22 '13 at 22:44
Thanks! Yes it is I just found the Network Mask Table, it depends on the class of the IP.… – Michael Gamage Sep 22 '13 at 22:55
@Michael can you submit this as an answer outlining your findings? – 50-3 Sep 23 '13 at 9:36
@50-3 : Done! :) – Michael Gamage Sep 24 '13 at 4:51
@Michael Gamage Ugh. Classful IPs have no been used in decades. it is all CIRD now. – Hennes Nov 16 '14 at 22:52
up vote 2 down vote accepted

Major Network Mask is always assigned by the class of the IP addresses used on the network.

If a network has Class A IP Addresses assigned to hosts, Major Network Mask is

Class A:

Class B:

Class C:

In my case, IP address is a Class A IP address,so the Major Network Mask is

share|improve this answer

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.