DDNS handling of "dumb" DHCP clients

Uwe Meyer-Gruhl dhcp_email at congenio.de
Thu Aug 9 12:15:20 UTC 2012

> I don't get to do this much these days, but my preferred method has
> been to manage the DNS myself for such hosts - and then refer to them
> by name in DHCP. Ie :
> host printer-x {
>   ...
>   fixed-address printer-x.somedomain.com ;

Sure - but in that case, we have to assign the IP addresses statically - 
which we actually still do.

Doing that is a problem when you use IP ranges with very large numbers 
of clients: There are NIC-imposed minimum utilizations which force us to 
permanently reconfigure the IP pools according to the number of PCs 
being serviced in the different shared networks. The renumbering of 
networks brings about the need to frequently change the fixed addresses 
of all the printers in the affected IP ranges.

This is why DHCP was invented in the first place: handing out dynamic 
addresses from a pool of available IPs. The DDNS update feature is then 
used to make the provisioned client devices addressable via non-changing 
DNS names.

There should be no need for a DHCP client to know its IP nor its DNS 
handle before it gets them from the DHCP server (nor to report it back 
via the FQDN option).

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