Re: DNS problem (forwarding order?)



On Thu, 2005-07-07 at 16:44 -0400, Dan Williams wrote:

> -----------------------------
> 3.8. Domain Name Server Option
> 
>    The domain name server option specifies a list of Domain Name System
>    (STD 13, RFC 1035 [8]) name servers available to the client.  Servers
>    SHOULD be listed in order of preference.
> -----------------------------
> 
> So it appears to say in the RFC (2132) that the servers should be
> contacted in order returned from the DHCP server.  

Well...yes, the spec says it's order of preference, but it's critical to
note here that DNS (being UDP based) is not a reliable protocol.  If for
instance the first (internal) server is heavily loaded and misses a
query from the client, then the client will fall back to one of the
secondary servers which won't have the internal addresses, and then he
loses.

So regardless, I think this is a bug in the network setup at wherever
David is.  He (and everyone else, regardless of whether or not they're
using NetworkManager, Windows, or whatever) will see this behavior
periodically if the internal server or the network is heavily loaded.
The network admins should fix it so only the internal server is
returned, and it forwards external requests.

That said, it is reasonable to try to make things more pleasant for him
to work around this bug.  From a quick look at the BIND source though I
don't see a way to change the policy :/

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