minimum expire time
Ted_Rule at flextech.co.uk
Ted_Rule at flextech.co.uk
Wed Sep 15 09:46:28 UTC 1999
As an extra consideration to add to the arguments for and against this - and I
don't presume to
say whether this is good or bad.., don't forget about the existance of
LoadSharing DNS solutions
"out there". See digs below for www.microsoft.com randomly jumping all over the
place as an example,
with 0S TTL's - actually, I feel it's slightly naughty that the www NS records
have such low TTL's as well,
but that's a whole other argument.
Perhaps some way of restricting the option as available to dialup connected
servers only or
a warning note in the documentation about the option's interaction with such
servers might
be worth having?
Maybe having different min-expire times on A records and other sorts of records,
so that NS
and MX records get bigger minimums than A records and LoadSharing DNS is less
affected
by the option?
Just a thought.....
Ted Rule,
Flextech Television
$ dig www.microsoft.com
; <<>> DiG 8.1 <<>> www.microsoft.com
;; res options: init recurs defnam dnsrch
;; got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 6
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 0
;; QUERY SECTION:
;; www.microsoft.com, type = A, class = IN
;; ANSWER SECTION:
www.microsoft.com. 0S IN A 207.46.130.149
;; Total query time: 219 msec
;; FROM: homer.flextech.co.uk to SERVER: default -- 195.188.171.98
;; WHEN: Wed Sep 15 10:24:07 1999
;; MSG SIZE sent: 35 rcvd: 51
$ dig www.microsoft.com
; <<>> DiG 8.1 <<>> www.microsoft.com
;; res options: init recurs defnam dnsrch
;; got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 6
;; flags: qr aa rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 0
;; QUERY SECTION:
;; www.microsoft.com, type = A, class = IN
;; ANSWER SECTION:
www.microsoft.com. 0S IN A 207.46.131.15
;; Total query time: 428 msec
;; FROM: homer.flextech.co.uk to SERVER: default -- 195.188.171.98
;; WHEN: Wed Sep 15 10:24:17 1999
;; MSG SIZE sent: 35 rcvd: 51
$ dig www.microsoft.com ns
; <<>> DiG 8.1 <<>> www.microsoft.com ns
;; res options: init recurs defnam dnsrch
;; got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 6
;; flags: qr rd ra; QUERY: 1, ANSWER: 2, AUTHORITY: 0, ADDITIONAL: 2
;; QUERY SECTION:
;; www.microsoft.com, type = NS, class = IN
;; ANSWER SECTION:
www.microsoft.com. 14m8s IN NS dd2.microsoft.com.
www.microsoft.com. 14m8s IN NS dd.microsoft.com.
;; ADDITIONAL SECTION:
dd2.microsoft.com. 14m53s IN A 207.46.138.7
dd.microsoft.com. 14m53s IN A 207.46.138.6
;; Total query time: 5 msec
;; FROM: homer.flextech.co.uk to SERVER: default -- 195.188.171.98
;; WHEN: Wed Sep 15 10:24:23 1999
;; MSG SIZE sent: 35 rcvd: 115
$ dig www.microsoft.com soa
; <<>> DiG 8.1 <<>> www.microsoft.com soa
;; res options: init recurs defnam dnsrch
;; got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 6
;; flags: qr aa rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 1, ADDITIONAL: 0
;; QUERY SECTION:
;; www.microsoft.com, type = SOA, class = IN
;; AUTHORITY SECTION:
www.microsoft.com. 10M IN SOA dd.microsoft.com. msnhst.microsoft.com.
(
3146376269 ; serial
6H ; refresh
15M ; retry
12w6d ; expiry
10M ) ; minimum
;; Total query time: 227 msec
;; FROM: homer.flextech.co.uk to SERVER: default -- 195.188.171.98
;; WHEN: Wed Sep 15 10:24:29 1999
;; MSG SIZE sent: 35 rcvd: 124
$ dig @dd.microsoft.com www.microsoft.com any
; <<>> DiG 8.1 <<>> @dd.microsoft.com www.microsoft.com any
; (1 server found)
;; res options: init recurs defnam dnsrch
;; got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 10
;; flags: qr aa rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 1, ADDITIONAL: 0
;; QUERY SECTION:
;; www.microsoft.com, type = ANY, class = IN
;; ANSWER SECTION:
www.microsoft.com. 0S IN A 207.46.130.149
;; AUTHORITY SECTION:
www.microsoft.com. 10M IN SOA dd.microsoft.com. msnhst.microsoft.com.
(
3146377272 ; serial
6H ; refresh
15M ; retry
12w6d ; expiry
10M ) ; minimum
;; Total query time: 221 msec
;; FROM: homer.flextech.co.uk to SERVER: dd.microsoft.com 207.46.138.6
;; WHEN: Wed Sep 15 10:41:12 1999
;; MSG SIZE sent: 35 rcvd: 140
$ dig @dd.microsoft.com www.microsoft.com ns
; <<>> DiG 8.1 <<>> @dd.microsoft.com www.microsoft.com ns
; (1 server found)
;; res options: init recurs defnam dnsrch
;; got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 10
;; flags: qr aa rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 0, ADDITIONAL: 0
;; QUERY SECTION:
;; www.microsoft.com, type = NS, class = IN
;; Total query time: 230 msec
;; FROM: homer.flextech.co.uk to SERVER: dd.microsoft.com 207.46.138.6
;; WHEN: Wed Sep 15 10:41:23 1999
;; MSG SIZE sent: 35 rcvd: 35
$ dig microsoft.com ns
; <<>> DiG 8.1 <<>> microsoft.com ns
;; res options: init recurs defnam dnsrch
;; got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 6
;; flags: qr rd ra; QUERY: 1, ANSWER: 4, AUTHORITY: 0, ADDITIONAL: 4
;; QUERY SECTION:
;; microsoft.com, type = NS, class = IN
;; ANSWER SECTION:
microsoft.com. 1d10h12m57s IN NS DNS5.CP.MSFT.NET.
microsoft.com. 1d10h12m57s IN NS DNS1.microsoft.com.
microsoft.com. 1d10h12m57s IN NS ATBD.microsoft.com.
microsoft.com. 1d10h12m57s IN NS DNS4.CP.MSFT.NET.
;; ADDITIONAL SECTION:
DNS5.CP.MSFT.NET. 4h33m53s IN A 207.46.138.12
DNS1.microsoft.com. 1d13h54m48s IN A 131.107.1.240
ATBD.microsoft.com. 1d13h54m48s IN A 131.107.1.7
DNS4.CP.MSFT.NET. 8h20m15s IN A 207.46.138.11
;; Total query time: 7 msec
;; FROM: homer.flextech.co.uk to SERVER: default -- 195.188.171.98
;; WHEN: Wed Sep 15 10:41:39 1999
;; MSG SIZE sent: 31 rcvd: 182
$ dig @dns1.microsoft.com www.microsoft.com ns
; <<>> DiG 8.1 <<>> @dns1.microsoft.com www.microsoft.com ns
; (1 server found)
;; res options: init recurs defnam dnsrch
;; got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 10
;; flags: qr rd ra; QUERY: 1, ANSWER: 2, AUTHORITY: 0, ADDITIONAL: 2
;; QUERY SECTION:
;; www.microsoft.com, type = NS, class = IN
;; ANSWER SECTION:
www.microsoft.com. 15M IN NS dd.microsoft.com.
www.microsoft.com. 15M IN NS dd2.microsoft.com.
;; ADDITIONAL SECTION:
dd.microsoft.com. 15M IN A 207.46.138.6
dd2.microsoft.com. 15M IN A 207.46.138.7
;; Total query time: 243 msec
;; FROM: homer.flextech.co.uk to SERVER: dns1.microsoft.com 131.107.1.240
;; WHEN: Wed Sep 15 10:41:55 1999
;; MSG SIZE sent: 35 rcvd: 102
$ dig @dd.microsoft.com www.microsoft.com a
; <<>> DiG 8.1 <<>> @dd.microsoft.com www.microsoft.com a
; (1 server found)
;; res options: init recurs defnam dnsrch
;; got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 10
;; flags: qr aa rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 0
;; QUERY SECTION:
;; www.microsoft.com, type = A, class = IN
;; ANSWER SECTION:
www.microsoft.com. 0S IN A 207.46.130.14
;; Total query time: 276 msec
;; FROM: homer.flextech.co.uk to SERVER: dd.microsoft.com 207.46.138.6
;; WHEN: Wed Sep 15 10:43:27 1999
;; MSG SIZE sent: 35 rcvd: 51
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