are there any benefits?

Jim Reid jim at mpn.cp.philips.com
Wed Aug 11 18:16:21 UTC 1999


>>>>> "David" == David  <david at wmol.com> writes:

    David> Are there any benefits of using our primary nameserver for
    David> querying outside addresses, and having our secondary
    David> nameserver used for queries for our internal network? Would
    David> it lower load on our NS's ?

Perhaps. The load of servicing DNS lookups should not be a significant
resource hog. [Unless you're doing Secure DNS and/or have bazillions
of resolvers firing queries at your name server.] Having said that, it
is a good idea to spread the load, if only to eliminate single points
of failure. Stick a name server on each LAN (or site) - it can be
master or slave (primary or secondary) for the local zone(s) - and
arrange for the resolvers on that LAN/site to send their queries
there. Another name server or two, perhaps at a nearby location, can
be configured as backups in the resolver configuratons, just in case
the local name server is dead.

BTW, other name servers don't care (or know) which name server is
master (primary) for a zone. It's not the case that they query the
master server first and only try a slave if that doesn't respond.
They're just given a bunch of randomly ordered NS records to try for
your zone. The RTT to each of your listed servers is measured. A
remote name server will send queries to whickever of your name servers
generally tends to reply quickest. This monitoring of RTTs is done
continually to take account of name servers that go away or come alive
as well as changes in the network topology.

    David> if so.. would I use the forwarders option ?

No. It's probably more bother than it's worth. Personally, I prefer
name servers to find things out for themselves by following NS records
instead of blindly forwarding queries to another name server. There
are some circumstances when forwarding might help - dial-up links to
the Internet for instance - but I doubt if these apply here.


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