Take the tour ×  Well I'm not sure whether I'm missing something
here. But all I've read is that if first octet of IP is within 0
- 127 then it is categorized as Class A subnet and
correspondingly Subnet Mask for this is but when I connect my
system to Apple airport then my system gets IP as however subnet
mask is not Please explain what I'm missing here.  Adapter
Information  If there is something like for apple router subnet
mask is calculated on some different flags then please let me
know.  share|improve this question There are no fixed subnet
masks. Read a little about what subnetting actually means :)
en.wikipedia.org/wiki/Subnetwork –  Oliver Salzburg Jun 8 '12 at
13:36 add comment  3 Answers  up vote 17 down vote accepted
Classful addressing has been relegated to the dustbin of
history, made obsolete by VLSM and CIDR. The only place it's
still used today is Cisco certification exams.  What you're
seeing here is VLSM (Variable Length Subnet Mask). VLSM has been
the norm on the Internet since 1995 or s