Wrong IP address from DHCP?

[Anders Biro]

Hello, we experience problems that DHCP clients are sometimes assigned
non-valid addresses that are really beyond our DHCP scope (192.168.0.0/24)
and this is a great mystery.
We have scanned the network for "rouge" DHCP servers with the MS DHCPLOC
utility with no success at all. The non-valid assignment claims to stem from
DHCP server 192.168.35.254 including the DNS-server 192.168.35.1 but no such
servers seem to exist (does not respond to ping nor portscanning)

Is this problem familiar? Are there any other troubleshooting techniques
that might be appropiate for this issue?

/Regards Anders

 

[BobC]

Hello, we experience problems that DHCP clients are sometimes assigned
non-valid addresses that are really beyond our DHCP scope (192.168.0.0/24)
and this is a great mystery.
We have scanned the network for "rouge" DHCP servers with the MS DHCPLOC
utility with no success at all. The non-valid assignment claims to stem from
DHCP server 192.168.35.254 including the DNS-server 192.168.35.1 but no such
servers seem to exist (does not respond to ping nor portscanning)

Is this problem familiar? Are there any other troubleshooting techniques
that might be appropiate for this issue?

/Regards Anders

Is this a wireless network? The affected computers may be connecting to
another wireless network and getting ip addresses assigned from there.

 

[Kurt]

Yes. And if this is a large network, someone may be bringing in a laptop or
something with a DHCP server that you can't find because they are only
connected for a short time. I'd look for the wireless thing first if you're
using wireless.

....kurt