DHCP IP Pool Utilization Issue in Infoblox

L01
L01
in DNS, DHCP, IPAM (DDI)

We are experiencing an issue with our Infoblox DHCP environment where the IP address pool frequently reaches 100% utilization, preventing devices from obtaining IP addresses automatically. To maintain network connectivity, we are currently releasing IP addresses manually on a daily basis.

The only related observation in the Infoblox portal is that six licenses are showing as expired. At this time, it is unclear whether this is contributing to the issue, and we would appreciate your guidance on whether this could be a potential factor.

Comments

  • jlw
    jlw

    Is the DHCP scope size inadequate or scavenging configured? Just something to look at before licensing for root cause..

  • L01
    L01

    Thanks for the suggestion. Our DHCP scope is a /24, which provides 254 usable IPs, and currently we only have around 30–40 devices. However, the DHCP pool frequently shows 100% utilization and stops assigning IP addresses to new devices.

    When I check from the GUI, only about 30 leases are actually active, while 10–15 IPs appear vacant. If I manually select these IPs and lease them, the devices get connectivity.

    This suggests that the issue may not be related to scope size or number of devices, and we are investigating why the DHCP pool shows full utilization despite free IPs.

  • jlw
    jlw

    What do the syslog messages for DHCP server on that member show? Can you open a support ticket? Those guys are helpful.

  • marcelv
    marcelv

    Check your lease time for that range. If you have different clients getting IPs in that subnet they could be holding onto leases too long and stopping new clients from getting IPs. This would be more applicable if this subnet is providing IPs to many different clients (like a guest Wifi network). Also - I don't think it's a good idea to make your DHCP scope a full /24 - what about your gateway router or VRRP addresses in that range/vlan? I typically create a scope that excludes the first 10 addresses in any given range. These are kept aside for infrastructure. So the usable scope is only around 244 odd devices. Apologies if this is irrelevant to your situation.

  • L01
    L01

    Thank you for the suggestions. I will verify the lease time for this range and check the exclusions for infrastructure IPs as you guided.@ marcelv

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