Dear all,
We have DHCP configured in our router(3600) all the pcs are getting the IP address from the DHCP pool. IP range and subnet mask as follows
10.19.92.X
10.19.93.X
10.19.94.X
10.19.95.X

255.255.252.0.

Now the problem is subnet mask is getting changed in all the Pcs randomly as class B or class A. We have to release and renew the IP address each and every time which becomes headache.
We appreciate your valuable feedback to fix this problem at the earliest.

Thanks
Asai

I'm not questioning your design, but do you have a reason for breaking down 8 hosts into 4 subnets? Security reasons maybe?

What OS are the hosts running? It almost sounds like Microsoft's auto-completing of the subnet mask when you are assign a host a static IP, but yours is happening on a DHCP network.

My mistake....I read your subnet mask as 255.255.255.252 instead of 255.255.252.0

Are the IP addresses also getting changed to 169.254.X.X when this happens as well?

"Republicans in Congress are moving to ratify a constitutional amendment to ban flag burning, thus ending the Iraq insurgency."

"255.255.252.0"
The above provides for 64 broadcast domains within the class B address range that allow for 4 IP addresses per domain.
The first of each is for the network ID and the fourth for Broadcast.
This leaves only two left over to be used for nodes.

Depending on what you want to do then you will need to adjust accordingly.

HTH
Bryan

Bryan,

Can you elaborate a little more on your response for my learning?

I follow most of it. Class B default mask is 255.255.0.0 If you borrow six bits, your mask becomes 255.255.252.0. 2^6 = 64 subnets.

255.255.252.0 in binary:

11111111.11111111.11111100.00000000

22 bits belong to the network, 10 are free for IP adddresses.

2^10 - 2 = 1022 useable IP addresses. I'm not following where you get 4 IP addresses per subnet. Wouldn't that be the case if the mask were 255.255.255.252?

http://www.weird.com/~woods/classb.html explains it pretty good with a chart.

HTH
Bryan

That web site doesn't seem to load for me.

The site loads very fast for me, even today, with the exception the Counter at the bottom of the page.

Bryan