Core DNS (follow-up)

We have received a few messages following our earlier post so this update attempts to address them.

Question: Certain people emailing me are still seeing bounced messages.

Answer 1: Some service providers will have old cached DNS records suggesting that mailscanner2.theitguys.co.uk is unavailable. The time-to-live on theitguys.co.uk is 2 hours, which means some service providers will not re-check the records until later today.

Answer 2: People emailing you may have sent a message on Monday and only just received a bounce. Mail servers by default are configured to retry for up to five days and then bounce a message back to the sender. They don’t always give an immediate bounce to a message.

Serious DNS issues can occur with service providers that cache DNS names and ignore the time-to-live records for the domain. Service providers that are known to do this include AOL, BT and Virgin.

We will keep you posted on the progress of this situation.

For the more technical amoungst us the correct DNS for mailscanner2 is:

$ dig mailscanner2.theitguys.co.uk mx @ns1.easynet.co.uk

; < <>> DiG 9.4.1-P1 < <>> mailscanner2.theitguys.co.uk mx @ns1.easynet.co.uk
; (1 server found)
;; global options:  printcmd
;; Got answer:
;; ->>HEADER< <- opcode: QUERY, status: NOERROR, id: 20069
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 2, ADDITIONAL: 3

;; QUESTION SECTION:
;mailscanner2.theitguys.co.uk.	IN	MX

;; ANSWER SECTION:
mailscanner2.theitguys.co.uk. 10760 IN	MX	5 mailscanner2.theitguys.co.uk.

;; AUTHORITY SECTION:
mailscanner2.theitguys.co.uk. 2794 IN	NS	ns2.theitguys.co.uk.
mailscanner2.theitguys.co.uk. 2794 IN	NS	ns1.theitguys.co.uk.

;; ADDITIONAL SECTION:
mailscanner2.theitguys.co.uk. 2794 IN	A	78.33.33.164
ns2.theitguys.co.uk.	2794	IN	A	82.109.198.9
ns1.theitguys.co.uk.	13331	IN	A	78.33.33.162

;; Query time: 20 msec

;; SERVER: 195.40.0.250#53(195.40.0.250)
;; WHEN: Thu May 22 12:58:05 2008
;; MSG SIZE  rcvd: 146

$ dig mailscanner2.theitguys.co.uk a @ns1.easynet.co.uk

; < <>> DiG 9.4.1-P1 < <>> mailscanner2.theitguys.co.uk a @ns1.easynet.co.uk
; (1 server found)
;; global options:  printcmd
;; Got answer:
;; ->>HEADER< <- opcode: QUERY, status: NOERROR, id: 47152
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 2, ADDITIONAL: 2

;; QUESTION SECTION:
;mailscanner2.theitguys.co.uk.	IN	A

;; ANSWER SECTION:
mailscanner2.theitguys.co.uk. 2634 IN	A	78.33.33.164

;; AUTHORITY SECTION:
mailscanner2.theitguys.co.uk. 2634 IN	NS	ns2.theitguys.co.uk.
mailscanner2.theitguys.co.uk. 2634 IN	NS	ns1.theitguys.co.uk.

;; ADDITIONAL SECTION:
ns2.theitguys.co.uk.	2634	IN	A	82.109.198.9
ns1.theitguys.co.uk.	13171	IN	A	78.33.33.162

;; Query time: 24 msec
;; SERVER: 195.40.0.250#53(195.40.0.250)
;; WHEN: Thu May 22 13:00:45 2008
;; MSG SIZE  rcvd: 130