DHCP handing zero address

Posted on 2010-11-22
Last Modified: 2012-06-21
I just ran into a client that was having issues connecting to our mail server and other sites. When I ran IPconfig to find out what IP address it was assigned I noticed that it had a .0 address, basically it had the network name as an IP address.  i.e.
I'm wondering why DHCP would hand out this address as it is not a valid IP address.

Any thoughts?
Question by:GW_Techno
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Expert Comment

ID: 34190773
Have you checked the allowed range of addresses configured in the DHCP scope ?
LVL 71

Expert Comment

by:Chris Dent
ID: 34190817

Depending on the accompanying subnet mask, is potentially a valid address. What is the subnet mask here?


Author Comment

ID: 34190837
Yes, basically my range is - *not the actual numbers but last two octets are correct.    So we actually have 1,024 available IPs in that range.  Microsoft DHCP server doesn't allow me to set exclusions to block the,x.x.46.0 and  x.x.47.0 from being handed out..

I didn't think it was possible to assign a dot zero address.
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Author Comment

ID: 34190847
we're using the subnet mask
LVL 71

Accepted Solution

Chris Dent earned 250 total points
ID: 34190913

That's a valid address then, or it should be. A range is whatever total, -2, one broadcast, and one subnet (1024 - 2 = 1022 useable). All addresses between, 0 and 255 included, are valid addresses.

Does whatever you're using refuse to talk to a host on that address?


Assisted Solution

ipajones earned 250 total points
ID: 34190992

Just following on from Chris-Dent's last comment:

If you're using the range - with a /22 mask ( then both and will be classed as valid addresses.  If you want to exclude them you may have to setup separate scopes.

Author Closing Comment

ID: 34192194
It wasn't until you mentioned the subnet mask that I realized that it was a good address.   I guess I never noticed .0 addresses being used.

Actually discovered that it was a corrupt image, or Office installation that was causing the problem.

Thanks for your help

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