Rather than applying lipstick to the pig, why not run a local
caching-only resolver? Move up and out of the stub-ville slums. A local
instance of named doesn't take up that much server resources (disk,
memory, CPU), and pays you back by *not*, as a stub resolver does, using
network resources, and incurring network latency, for each and every lookup.
- Kevin
Taylor, Gord wrote:
I should mention, that I've looked at "options rotate", but the concern is that this will mean retransmits if ANY of the nameservers are down. So, any DNS outage would cause some level of impact to the application.
It also makes it harder for applications to determine if slowdowns are due to
DNS name resolution issues. Since 1/3 of the queries will be slower, they'll
not think to look at DNS as root cause; they'd probably see it as a utilization
issue, or something along those liens. While that may mean I don't get paged,
it's not great for the business :)
Gord Taylor (CISSP, GCIH, GEEK)
-----Original Message-----
From: bind-users-boun...@lists.isc.org
[mailto:bind-users-boun...@lists.isc.org] On Behalf Of Taylor, Gord
Sent: 2009, July, 15 10:05 AM
To: bind-users@lists.isc.org
Subject: A smarter stub resolver??
I've frequently run into a problem that the stub resolver just isn't
very dynamic in its selection of name servers - especially when dealing
with time-sensitive apps. If the first DNS server in the list is down,
the applications may slow down due to the constant retransmits. Given a
resolv.conf like the one below, the xNix box will ALWAYS query the first
DNS server, event if it's down. So, every single DNS query (think of how
many reverse lookups a mail server, or Kerberos will do), there's a 2
second delay.
Is there a "smarter" stub resolver that acts more like a DNS server
using Round Trip Time (RTT) to pick the "best" DNS server from the list?
We run well over 500 xNix boxes (and growing), so running DNS on each of
these just isn't a viable option to get round the DNS timing issues.
Nameserver 10.10.10.1
Nameserver 10.10.10.2
Nameserver 10.10.10.3
Options retry:2
Options retrans:2
Gord Taylor (CISSP, GCIH, GEEK)
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