Inquiry Regarding DHCP Server IP Allocation Issue

[frosten5117]

I am reaching out regarding an issue we are experiencing with our DHCP server configuration. Despite setting a specific DHCP IP range, users are receiving IP addresses that fall outside of the defined range.

Our current DHCP settings are as follows:

DHCP Range: 10.135.4.11 - 10.135.4.200
Client Addressing: Run a DHCP server
Lease Time: 1 week
Custom Nameservers: HQdns1, HQdns2, 8.8.8.8, 8.8.4.4
Boot Options: Disabled

There are no additional DHCP options configured, and we have not set any fixed IP assignments.

However, we continue to observe that some clients are being assigned IP addresses outside this specified range.

We have verified that no additional DHCP server should be influencing these assignments and have checked for possible configuration issues on the client devices.

Could you please assist us in identifying the potential cause of this issue and suggest any adjustments to our settings that might help to enforce the specified IP range?

[PatWruk]

I would start with a packet capture on the network while you connect one of the devices and see if there are any dhcp responses coming from a device you don't recognize, or that isn't your MX.

Are the IPs in the same subnet just below 11 or above 200? or completely different subnet?

[cmr · Accepted solution]

@frosten5117 there must be another DHCP server on your network, either that or the range configuration hasn't been properly applied.  Can you share a screenshot of where you have set the range?

You should have something like this:

[frosten5117]

According to your explanation, it seems that I have completely misunderstood and applied the settings in the opposite way.

[cmr]

@frosten5117 indeed, I do wish it said excluded rather than reserved, it is very confusing.