DHCP wont lease ip while there is free IP

[#1]

Hi Team,

i have some issue on the customer that they are running NIOS 8.2 with DHCP service activated. The DHCP wont lease IP to the new client while the IP status is free. To make the DHCP lease i have to cleare lease manually. AFAIK dhcp should lease the ip when the IP is available (free).

Any suggestion for this case?

Thanks

[#2 · Accepted solution]

There are multiple reasons for why this may happen. To start investigating this, you would first need to review the corresponding system log messages and this should give you a better idea on what both the server and the client are doing.

You can open the system log viewer (Administration -> Logs -> Syslog and select the DHCP server from the Member dropdown menu if necessary). To find the relevant log messages, click on the Show Filter link and in the Choose Filter menu, select Message. Set the next menu to Contains and in the text box, enter the MAC address for the client. Click Apply to view only the log messages that contain this MAC address.

The next step in troubleshooting this would be to run a network sniffer on the client so that you can see all packets going to and from it. This will allow you to see if there is anything that the DHCP server is not part of that might be affecting the clients requests.

For further assistance with troubleshooting this, be sure to reach out to Infoblox Support and they can help walk you through all of this.

Regards,

Tony

[#3]

Thank you very much for the detailed steps for Tshoot.

However, is there a way to change the timeout in Infoblkox DHCP server to expire all information related to a recently freed lease? IS there a way to change the time to re-use a previously leased IP?

[#4]

We've run into this too.  I was doing the manual method but I just ran across a option, DHCP scavenging.  This can be set at a higher level or down to the individual DHCP pool.  Edit the DHCP range, not the IP Network range.  Toggle the Advanced button and under IPv4 DHCP Options, you can click Advanced.  There's where you'll see the options for the scavenging.  

-Andrew