Hi all,
I have some caching resolvers that are running BIND 9.4.3. They
answer about 30k-ish recursive queries per second at peak hours.
Every couple of weeks or so, we get calls to customer support with
complaints that the www.capitalone.com web site is unavailable.
The CNAME for www.capitalone.com points to www.wpex.capitalone.com,
which is served out by a different set of name servers:
wpex.capitalone.com. 3600 IN NS
ns2-mockingbird.wpex.capitalone.com.
wpex.capitalone.com. 3600 IN NS
ns1-cardinal.wpex.capitalone.com.
those name servers are, apparently, occasionally unavailable, at least
from our network, and we end up with a negative cached record that I
suspect lasts 48 hours.
right now, I am doing a workaround with a shell script that looks
something like this (this is just a snippet, btw, not the full script):
rndc dumpdb
if [ `grep capitalone.com /var/dump/named_dump.db | grep -q
NXDOMAIN` ]; then
rndc flushname `grep capitalone.com | grep NXDOMAIN | awk '{print $1}'`
This may not be the only host/domain that we have occasional
difficulty with, but it's certainly the only one that has calls from
CS that get filtered down to me. Is this something broken in our
resolvers, or is this (as I suspect) just a really wonky and somewhat
broken implementation on the part of capitalone.com? Is anyone else
having difficulty with resolution of this domain?
Here's a dig from one of our name servers. (the dig is from my
workstation which has 9.4.2-P2 on it).
; <<>> DiG 9.4.2-P2 <<>> +trace @wdmdc-dns1 www.capitalone.com
; (1 server found)
;; global options: printcmd
. 242071 IN NS K.ROOT-SERVERS.NET.
. 242071 IN NS H.ROOT-SERVERS.NET.
. 242071 IN NS J.ROOT-SERVERS.NET.
. 242071 IN NS L.ROOT-SERVERS.NET.
. 242071 IN NS B.ROOT-SERVERS.NET.
. 242071 IN NS D.ROOT-SERVERS.NET.
. 242071 IN NS M.ROOT-SERVERS.NET.
. 242071 IN NS I.ROOT-SERVERS.NET.
. 242071 IN NS E.ROOT-SERVERS.NET.
. 242071 IN NS F.ROOT-SERVERS.NET.
. 242071 IN NS A.ROOT-SERVERS.NET.
. 242071 IN NS C.ROOT-SERVERS.NET.
. 242071 IN NS G.ROOT-SERVERS.NET.
;; Received 512 bytes from 12.207.232.47#53(12.207.232.47) in 17 ms
com. 172800 IN NS K.GTLD-SERVERS.NET.
com. 172800 IN NS C.GTLD-SERVERS.NET.
com. 172800 IN NS A.GTLD-SERVERS.NET.
com. 172800 IN NS M.GTLD-SERVERS.NET.
com. 172800 IN NS L.GTLD-SERVERS.NET.
com. 172800 IN NS J.GTLD-SERVERS.NET.
com. 172800 IN NS D.GTLD-SERVERS.NET.
com. 172800 IN NS I.GTLD-SERVERS.NET.
com. 172800 IN NS F.GTLD-SERVERS.NET.
com. 172800 IN NS G.GTLD-SERVERS.NET.
com. 172800 IN NS B.GTLD-SERVERS.NET.
com. 172800 IN NS E.GTLD-SERVERS.NET.
com. 172800 IN NS H.GTLD-SERVERS.NET.
;; Received 508 bytes from 192.203.230.10#53(E.ROOT-SERVERS.NET) in 68
ms
capitalone.com. 172800 IN NS ns1.capitalone.com.
capitalone.com. 172800 IN NS ns2.capitalone.com.
capitalone.com. 172800 IN NS ns3.capitalone.com.
;; Received 138 bytes from 192.52.178.30#53(K.GTLD-SERVERS.NET) in 130
ms
www.capitalone.com. 120 IN CNAME www.wpex.capitalone.com.
wpex.capitalone.com. 3600 IN NS
ns2-mockingbird.wpex.capitalone.com.
wpex.capitalone.com. 3600 IN NS
ns1-cardinal.wpex.capitalone.com.
;; Received 148 bytes from 199.244.214.107#53(ns3.capitalone.com) in
42 ms
-rich goodson
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