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I'm experiencing some issues with some DHCP clients, sometimes they cannot get DHCP leases. My company has a Windows Server 2016 DHCP server with a failover twin server, both are also domain controllers.

While the problem is happening, I ran wireshark listening to the broadcast traffic from another PC. I could see the DHCP request from the client and also the server's offer, but after this exchange the client doesn't get the IP and simply sends another request after a while.

I cannot understand where the problem can be.

Tobia
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  • Is the client's problem that of getting a new DHCP lease after boot, or that of renewing its lease? Does the problem clear up after some time? Do the DHCP servers do load balancing? – harrymc May 06 '21 at 08:22
  • Does Wireshark on the client itself see the offer? Have you tried comparing the 'working' and 'non-working' offers (especially the ethernet headers)? How frequent is that "sometimes" -- does it go away on its own, or does it need a reboot, or something else? Is the client reachable if you configure a static IP address for it locally? Are the clients virtual machines? – user1686 May 06 '21 at 08:31
  • @harrymc the issue seems to be to get a new lease, the renewal works. I have tried to attach a new ethernet port with a new mac address, and the issue was the same. Even the dhcp server reboot doesn't help. After some time (hours) the problem disappears and dhcp starts working again. – Tobia May 08 '21 at 06:34
  • @user1686 Wireshark was monitoring the same network from another client, I could see the request from client and the offer from dhcp server and no more. While I have this issue, the dhcp doesn't work for any new devices and it works only for renewal, then I cannot compare good and wrong offers. This problem happens twice a month and after a couple of hours it disappears. Client/Server reboot doesn't solve. If I manually set the IP address the client works. Clients are notebook and PC, no VM, but servers are 2 Windows Server 2016 VM in a VMWare cluster, they are both domain controller. – Tobia May 08 '21 at 06:38

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