DDNS-Updates with nsupdate or compareable

Kevin Darcy kcd at daimlerchrysler.com
Tue Jan 14 00:25:44 UTC 2003

Falk Husemann wrote:

>Since there seems to be so  mutch fun possible with the DNS and BIND I
>recently registered my own domain and ordered a dynamic Zone. Now there
>is a small problem with the scriptability of nsupdate. I simply don't
>get, how to set the file which can be given to nsupdate with the update
>commands. How can I use nsupdate in a script?
Just give the input file as the last parameter on the command line, or 
pipe the commands to nsupdate.

>And how can I update a domain (macknolle.de for example), not a
At a zone cut, I believe nsupdate defaults to changing data in the child 
zone rather than in the parent -- if you want to override this (because 
you want to add/change/delete delegation records), then you need a BIND 
9-derived nsupdate, which has the "zone" command. Given this default 
behavior, you shouldn't have any problem adding/changing/deleting 
non-SOA zone-apex data, e.g. NS records (as long as you don't delete 
them all), A records, MX records. Be aware that by standards fiat you 
cannot add or delete an SOA record via Dynamic Update. You can, however, 
atomically _change_ an SOA, as long as the serial number is incremented 
(otherwise the change gets silently ignored); just treat it as an "add" 
in nsupdate.

By the way, it is wise to fully-qualify and dot-terminate all names in 
nsupdate commands, because some versions parse names similarly to how 
they are parsed in master files, i.e. unqualified names get the name of 
the zone appended to them, which is often not what you want.

                                - Kevin

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