DHCP problem

Question

Hello! Can anybody tell me why does Windows Server 2012 DHCP service stop giving out IP addresses as soon as the number of available addresses plunges to 4?

Why doesn't it just first give out all 100% of addresses before stopping assigning ip addresses? I mean in 100% of cases I see that when there are 4 IPs left in the scope my DHCP service stops allocating addresses to clients and if - for example - my scope consists of 100 addresses only 96 clients can be assigned IPs from the scope... Regards,
Michael

Answer 1

Hello, It is recommended to enable DNS ageing and scavenging. Adjust the lease duration and cleanup interval settings. If problem persists, we may use network capture tool (such as Network Monitor) to monitor DHCP lease process --DORA process (Discover, Offer, Request, Acknowledge) about the new client on network, it would be helpful to identify the details. DHCP Client States in the Lease Process: https://learn.microsoft.com/en-us/previous-versions/windows/it-pro/windows-2000-server/cc958935(v=technet.10)?redirectedfrom=MSDN

---If the Answer is helpful, please click "Accept Answer" and upvote it.

Answer 2

Hello Karlie Weng, Thank you for the reply - I'll take a look at the article! Regarding the number 4: do I get it right that DHCP server does not have any restrictions that would be stopping it from assigning IPs when there're only 4 addresses left? Regards,
Michael