Chuck Swiger
cswiger at mac.com
Thu Nov 29 23:39:47 UTC 2012
On Nov 29, 2012, at 3:34 PM, Jose Manuel Delgado G. wrote:
> about the other question, as to reduce the response time of my server when the domain does not exist?
BIND implements negative caching of NXDOMAIN responses:
% dig www.does.not.exist. @localhost
[ ... ]
;; ->>HEADER<<- opcode: QUERY, status: NXDOMAIN, id: 4942
;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 1, ADDITIONAL: 0
;; QUESTION SECTION:
;www.does.not.exist. IN A
;; AUTHORITY SECTION:
. 10800 IN SOA a.root-servers.net. nstld.verisign-grs.com. 2012112901 1800 900 604800 86400
;; Query time: 360 msec
;; SERVER: 127.0.0.1#53(127.0.0.1)
;; WHEN: Thu Nov 29 18:35:52 2012
;; MSG SIZE rcvd: 111
% dig www.does.not.exist. @localhost
[ ... ]
;; ->>HEADER<<- opcode: QUERY, status: NXDOMAIN, id: 55697
;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 1, ADDITIONAL: 0
;; QUESTION SECTION:
;www.does.not.exist. IN A
;; AUTHORITY SECTION:
. 10789 IN SOA a.root-servers.net. nstld.verisign-grs.com. 2012112901 1800 900 604800 86400
;; Query time: 1 msec
;; SERVER: 127.0.0.1#53(127.0.0.1)
;; WHEN: Thu Nov 29 18:36:03 2012
;; MSG SIZE rcvd: 111
Regards,
--
-Chuck
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