"name already in use" message in dymanic update

[Kevin Darcy]

This is not the responsibility of a DNS server. It just simply accepts or
rejects Dynamic Updates based on the prerequisites (if any) in the requests
and/or its local security policy. It has no business "rewriting" requests that
it receives. If the nameserver did this, how would the DHCP server know what
record was added? It couldn't trust that the name it requested was added, and
it can't rely on a reverse lookup to determine this, since the PTR record may
reside on a totally different master and therefore wouldn't reflect the correct
name. So I don't see how one could get reliable forward/reverse consistency if
the nameserver is going off and doing this "rewriting" stuff behind the scenes.

You should investigate whether your DHCP server can implement this
"name-hunting" logic -- seems like Cisco misdesigned this functionality and put
the algorithm in the wrong component. Then again, maybe they're just pulling
the old Microsoft trick of trying to coerce you into only using their
products...


- Kevin

Eulogio Robles P. wrote:

> We are using Bind 9.1.2, and it is being dynamically updated from a Cisco
> DHCP server. We are getting these error message in syslog :
>
> May 30 16:50:14 dns1 /sbin/named[16196]: dynamic update failed: 'name not in
> use' prerequisite not satisfied (YXDOMAIN)
>
> We suppose that it is because the name is already being used by other host.
> As we cannot control the name that a client PC has configured, we would like
> the behaviour that is present in Cisco's own DNS implementation : it appends
> a serial number to the host name if it is already present (if "mypc" already
> existe, it tries "mypc1", "mypc2", etc), until is finds a new name. Is there
> such an option in  Bind?
>