SRV Record Priority set by IP Address

[Matus UHLAR - fantomas]

On 20.07.09 13:26, Lev Vanyan wrote:
> i've stumbled into a question whether it is possible to configure BIND
> in a way that it responds to DNS SRV requests with the priority flag
> changed depending on the IP address of the requesting party.
> For example,
> there are two SRV records for _foobar._tcp. One points to 10.0.1.2 and
> the other to 10.0.2.2. The requesting party has the ip address
> 10.0.1.53. I would want to have the first one with the priority higher
> than the second, which would allow me to split up the network by zones
> each one having their own server with the rest of servers used only in
> case of the prevalent zone server failure.

Do you mean that bind could/should sort responses depending on source
address of client requesting the data in the manner to the servers
topologically closer to the client should precede others?

The "sortlist" option should do that. However, to benefit of this sorting,
all SRV records should have the same priority (so maybe you don't need SRV
here at all).

Also, the client (or intermediate relay, e.g. local DNS cache or nscd) must
not re-sort responses, but has to use them in the order they came in. That
may be problem in some libraries, some time ago I've been having similar
problems, it seemed that nss_lwres was responsible for that.

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