On Mon, 10 Sep 2001, Kris Benson wrote:
> George Kirikos wrote:
> >
> > NS2 would be accessed automatically if NS1 is unreachable, and
> > vice-versa.
>
> According to experiences on this list, that is not true in practice.
>
> The root nameservers return whichever one they feel like at the time, and
> the client contacts that server. If the server is down, you're SOL.
>
> Of course, who knows exactly how things are supposed to work or how things
> are coded to work...
>
The one the root nameservers are returning are probably based on the same
algorithm bind uses to figure this out since most, if not all of the
roots run on bind or a variation thereof, (except Z.ROOT-SERVERS.NET which
runs a proprietary verion of INEGroup's BINDPlus ;)
If they don't already know they should query every nameserver delegated
for domain and measure the RTT (Round Trip Time) from each in its
response. They then hand out the nameserver with the shortest RTT.
Then, each time they hand out that nameserver, they decrement the
RTT's of the rest in order to facilitate a bit of load balancing.
All this and more at the "Ask Mr. DNS" section of acmebw.com,
http://www.acmebw.com/askmrdns/archive.php?category=83&question=3
-mark
--
mark jeftovic
http://www.easydns.com
http://mark.jeftovic.net
