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DHCP config missing default gateway

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5 replies

by jogo

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I have this problem with some computers missing the default gateway, all others settings are correct. I have moved those PCs to a different port/switch and after releasing/renewing the IP sttings some aquire the right info but I can't point to anything as it happens intermittently.
We have Cisco 3550 multilayer switches connecting all PCs and this school has been moved to it's own VLAN/SUBNET recently, (we have done this with 10 other schools in the district)and have not seen anything like this.
Any suggestions?
Thank you in advance
JOGO

5 replies

by vic

Almost sounds like there's something else on that subnet (other than your dhcp server) performing dhcp. Have you checked this?

by adembo

I agree that you should check for rouge DHCP, but what about the IP address it gets? Is is the same IP as before when it did not have the default gateway or does it change? Had those systems ever been statically assigned anything, WINS, DNS.....?

I guess to troubleshoot, I would un-authorize your DHCP, and then see if you can obtain an IP. If so, then your problem is evident, if not, then maybe create a new Zone for DHCP and see if that helps.

by sgt_shultz

not to much to go on here.
what os on these problem boxes? you can't reproduce it? what have you tried to fix it? anything in the event logs on the problem boxes. when this happens how do you fix it. what is your symptom. no internet?

by jogo

Thank you for your sugestions, I failed to mention we have 2 DHCP servers each with a scope for that VLAN/SUBNET. After paying close attention to the IPs of the trouble machines I was able to pinpoint to one of the servers, I asked the Admin to check and sure enough! SCOPE WAS THE PROBLEM!
Thank you again

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