Activate IP conflict detection

[#1]

Hi,

I'm a new user of Infoblox DDI (v. 8.2.5) and I'm looking for how to enable ip address conflict detection.

What I want, is that before assigning an IP, Infoblox ping to make sure the IP is not already in use on the network (by a manually configured pc for example). This is to avoid IP address conflicts.
I had this option on my old DHCP server (Windows DHCP), but I do not find this feature in Infoblox.

Someone can help me ? and tell me if this feature exists and where can I configure it ?

Thanks

[#2 · Accepted solution]

Hi,

As far as i know, infoblox by default will do ping check when it lease an ip, when the ip is reply than you can see status on the lease tab as abandoned IP, and the IP will not be leased. Infoblox will automatically give next available IP address.

[#3]

Hi,

That's what I thought but i have a case with a conflict IP, so i try to know how is it possible.

My case :

Infoblox withc scope 192.168.1.10 to 99

PC 1 with DHCP 192.168.1.99

I shut the PC

I start PC 2 with manual address 192.169.1.99

I start PC 1 with DHCP

Infoblox still give PC i the IP 192.168.1.99

I have a conflict IP

I'll check status on the lease tab if i can see something.

Thanks

[#4]

Do the Infoblox DHCP logs show a full DORA (discover, offer, request, and acknowledgement)???

Windows 10 (since even 7 I think) remembers the last IP used by DHCP, so when you turn off a PC, it will try to reuse the existing IP when it's started up again.  Instead of typical DORA process to get a new IP, it starts a renewal with a DHCPREQUEST, to which DHCP will respond with DHCPACK.  At this point, it's up to the host to determine it has a duplicate.  It should start the DORA process at that point.

[#5]

Hi,

That was the problem, PC1 did not make a full DORA (confirmed by a wireshark capture).

I did a test with ip phone and it was OK. IP conflict detection is enabled on infoblox by default.

I checked in the lease tab and the IP is marked abandoned.

Everything works well now.

Thank you for helping me guys

[#6]

I know this is an old post but what was the issue with PC1?  What was done to resolve the issue?