Hostname differences between servers

Eugene Grosbein eugen at grosbein.net
Tue Oct 2 17:59:26 UTC 2018


02.10.2018 21:53, Norman Elton wrote:

> In our environment, we have multiple routers (VRRP) forwarding
> requests to two DHCP servers, run in failover. So if a client
> broadcasts out a DHCPREQUEST, that message is handled multiple times.
> Not a big deal, it's been working great for years.
> 
> We've just noticed that, sometimes, the hostname reported by the two
> servers don't match each other. For instance:
> 
> Oct  1 01:03:48 landlord01: DHCPREQUEST for 10.45.13.196
> (128.239.10.121) from e8802ea2eb7f (Michaels-iPhone) via 10.45.13.2
> Oct  1 01:03:48 landlord02: DHCPREQUEST for 10.45.13.196
> (128.239.10.121) from e8802ea2eb7f (android-9375f90cad51e32f) via
> 10.45.13.2: lease owned by peer
> 
> So, is it an android, or is it an iPhone? In this case, the mac
> address points to Apple, but why is one server reporting the hostname
> is android-9375f90cad51e32f?
> 
> This is happening fairly frequently. Our servers are running the
> RHEL-provided version of ISC dhcpd, 4.1.1-61.P1.el6_10.
> 
> Any ideas?

First, you should use tcpdump -enpvvvs0 to see more details of requests
and look for differences as they have much more parts than dhcp servers shows.

You may be having un- or mis-configured dhcp relay/proxy in the network duplicating requests.



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