If I change the subnet mask on my network will it effect the DNS server there? I just did an upgrade from 03 to 08 AD and when i did the upgrade i by accident put the subnet mask at, ive then changed the pc's to the same. It was and our router also has Seems like since I did this the DNS has been "flaking out"




Changing the subnet mask from to will halve your subnet range of IPs.

You need just to make sure that all needed services including the default gateway resides in the same subnet. Otherwise, you may end up having some PCs/servers in two separate subnets.

  • Ah...and the light bulb goes off! Ok I understand now. I'm a SQL/C# developer by nature not a network admin so I had to ask as Im the only IT guy for the company here. Thanks! – GabrielVa Jan 25 '12 at 14:43

You cut the IP space in half by changing the subnet mask. If you have IPs in the .1 to .127 range, they will not be able to communicate with any IPs in the .128 to .255 range. This has little to do with DNS.

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