How to trigger a DNS update?

John Hascall john at iastate.edu
Fri May 11 13:23:24 UTC 2012


[background]
We have a "NetReg" system that builds a dhcpd.conf file.
One of the things IT admins like to do is rename hosts.
So, version N of the config file might have:

host 0f1f9faf2fcc {
        hardware ethernet 0f:1f:9f:af:2f:cc;
        ddns-hostname "jo-blah";
        ddns-domainname "admin.iastate.edu";
        option domain-name "admin.iastate.edu";
}

and version N+1 might have:

host 0f1f9faf2fcc {
        hardware ethernet 0f:1f:9f:af:2f:cc;
        ddns-hostname "joe-blah";
        ddns-domainname "admin.iastate.edu";
        option domain-name "admin.iastate.edu";
}

Not unexpectedly, when dhcpd is restarted with this new config file,
this doesn't actually cause DHCP to change the hostname in DNS.
It doesn't even appear that it happens when the lease is renewed.

So when does it happen?   And is there a way to make it happen faster?

Or am I better off just using DDNS outside of DHCP to update the DNS
record (that is, can I be sure DHCP will not somehow revert it)?


Thanks,
John


-------------------------------------------------------------------------------
John Hascall, john at iastate.edu
Team Lead, NIADS (Network Infrastructure, Authentication & Directory Services)
IT Services, The Iowa State University of Science and Technology


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