TTL's set to 1 second

Mark_Andrews at isc.org Mark_Andrews at isc.org
Fri Jan 31 23:56:02 UTC 2003


> Hi all,
> Our internet DNS host has set the TTL's for our DNS data to 1 second.  As I
> understand it, such a small TTL essentially causes our DNS data to not get
> cached anywhere, expiring nearly immediately after being looked up and
> cached.  This then increases the load on our authoritative DNS servers (our
> DNS host's servers) and the network/internet because the data is never
> cached anywhere longer than 1 second.  Is this correct?

	It also increases the load on the parent servers.  It
	increases the load on the servers of everyone who wants to
	contact you.  At the very least ensure that the NS records
	and the A records for the nameservers have a long time to
	live.

	The only reason the DNS works is that caching prevents key
	elements being overloaded.

	Mark
 
> Here's a query for our SOA record (with pertinent details ommitted):
> 
> bash-2.03# dig @ds1.ourdnshost.com ourdomain.com SOA
> 
> ; <<>> DiG 9.1.3 <<>> @ds1.ourdnshost.com ourdomain.com SOA
> ;; global options:  printcmd
> ;; Got answer:
> ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 3747
> ;; flags: qr aa rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 2, ADDITIONAL: 2
> 
> ;; QUESTION SECTION:
> ;ourdomain.com.             IN      SOA
> 
> ;; ANSWER SECTION:
> ourdomain.com.      1       IN      SOA     ds1.ourdnshost.com.
> support.ourdnshost.com. 2003012807 10800 3600 604800 1
> 
> ;; AUTHORITY SECTION:
> ourdomain.com.      1       IN      NS      ds1.ourdnshost.com.
> ourdomain.com.      1       IN      NS      ds2.ourdnshost.com.
> 
> ;; ADDITIONAL SECTION:
> ds1.ourdnshost.com.   1       IN      A       XXX.XXX.96.2
> ds2.ourdnshost.com.   1       IN      A       XXX.XXX.97.214
> 
> ;; Query time: 9 msec
> ;; SERVER: XXX.XXX.96.2#53(ds1.ourdnshost.com)
> ;; WHEN: Fri Jan 31 18:08:36 2003
> ;; MSG SIZE  rcvd: 160
> 
> Thanks in advance for any info.
> -BB
> 
> 
--
Mark Andrews, Internet Software Consortium
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742                 INTERNET: Mark.Andrews at isc.org


More information about the bind-users mailing list