subnetting question

[laruecl]

Hi all,
I am preparing for the CCNA and have come across a question that has me a little confused. The question reads, "What subnet is the address 200.17.49.200 /23 a member of?"
I thought that a 200 address was class c and couldn't use a /23 CIDR.
If someone could explain this I would really appreciate it.
Thanks

 

[KiscoKid]

200.x.x.x is a Class C network however in today's networking world, you can subnet/supernet for better addressing efficiency. Classful addressing has become largely obsolete and classless networking is the way forward. CIDR relies heavily on classless addressing. The concept of CIDR is to introduce supernets to allow more efficient address space advertisments within the Internet.

Therefore 200.17.49.200/23 subnet belongs to 200.17.48.0/23. This subnet incorporates both the "Class C" subnets of 200.17.48.0/24 and 200.17.49.0/24.

If you need more info, just search for CIDR or supernetting in Google. There will be lots of good info about it.