pooley Posted March 22, 2019 Posted March 22, 2019 Posting as I can no longer see the wood for the trees. Our DC fell over yesterday and stopped issuing DHCP addresses. (Forget what the error was - haven't slept much) Uninstalled the dhcp role and reinstalled, authorized and waited. No ip addresses were being issued (Or the clients weren't able to get them) Uninstalled the role and installed the role on a different server. Same result, server says it's working, clients not picking up any addresses. Someone give me some basic troubleshooting stuff please, i'm knackered and i'm 99% i'm missing something obvious and the 100% it's going to be bl00dy DNS Cheers Si
pooley Posted March 22, 2019 Author Posted March 22, 2019 Firewall letting DHCP through? Turned it off just in case, but thanks.
pooley Posted March 22, 2019 Author Posted March 22, 2019 Curriculum is flat, managed by LA, they haven't notified us of any changes.
36Degrees Posted March 22, 2019 Posted March 22, 2019 Have you tried restarting the DNS service on each of your DNS servers? Last random issue I had after a major system failure DNS appeared to be working correctly. Spent hours troubleshooting to no avail. After speaking to someone with far more server knowledge than me they said it sounds like a DNS issue, which I'd already ruled out. Nothing to lose / quick process so I restarted the DNS service on each server. Issue immediately disappeared...
pantscat Posted March 22, 2019 Posted March 22, 2019 Use wireshark to do some sniffing... you should be able to see if Discover, Offers, Requests and Acknowledgements are flying around the network. (https://wiki.wireshark.org/DHCP) That'll be a good start.
houlta Posted March 22, 2019 Posted March 22, 2019 You need to install wireshark on the server and a client and see whats going on. EDIT: Ninja'd, lol. 1
Mark182 Posted March 22, 2019 Posted March 22, 2019 Do your switches have spanning tree enabled? Could be a loop back unless I'm missing the point and your DC fell over as in broke and not just the DHCP side of things are broke.
pooley Posted March 22, 2019 Author Posted March 22, 2019 Spanning tree enabled, restarted dns, thinking of turning one dns server service off to troubleshoot. Now trying to learn wireshark quickly
howartp Posted March 22, 2019 Posted March 22, 2019 Just type "DHCP" in the "Apply a display filter..." box; that's the quick shortcut to filter only DHCP traffic.
pooley Posted March 22, 2019 Author Posted March 22, 2019 Right it's back, not sure why it stopped. Installed it on server #3 and it started working immediately. Why #1 and #2 wouldn't work is a problem for another time (maybe never) Thanks for the help guys Si
ADMaster Posted March 22, 2019 Posted March 22, 2019 A few more obvious things to check since you removed the role and added it back. I'm not sure if that keeps all the configuration or not. 1. Is the dhcp service running? 2. Is the scope properly configured and active? To eliminate any other networking / switch issues, connect a pc to the same switch / vlan as the server. If you have vlans, ip helper addresses? You don't have allow list only, or the network access protections to drop packets do you?
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