Re: [dhcwg] WGLC on draft-ietf-pcp-dhcp-03

[Ted Lemon <[e-mail]>]

On Jul 27, 2012, at 4:16 PM, Bernie Volz (volz) wrote:
The http://datatracker.ietf.org/doc/draft-ietf-dhc-option-guidelines does seem to indicate your solution, but it never specifies “when” this resolution should be done. I think that’s likely and issue we need to discuss about this guidelines draft.

That's an implementation issue; the same issue exists on the client.   Since you're setting up a tunnel, obviously the resolution happens when you set up the tunnel, and if the DNS changes after that, the client doesn't notice, tear down the tunnel, and set up a new one, does it?

As for how the server handles it, that's left up to the implementation.   The ISC DHCP server does the resolution when the request comes in, and if the DNS is down, it blocks.   Nominum's server does the resolution at request time too, but is a log smarter about not blocking and about responding if no answer comes from the DNS.   But really, if the DNS is down, you're hosed anyway, no matter who is doing the resolution.   You have to have reliable DNS.