force others' dns server to return authorative answers

Barry Margolin barmar at
Tue Mar 7 22:44:24 UTC 2000

In article <8a3m0m$4sm$1 at>,  <aliko at> wrote:
>How do I force them to discard their info from their cache and uses the
>new information from our primary dns server? (I found out the mail
>exchanger in our secondary server for our domain is incorrect but I
>cannot change it because it belongs to our web hosting company and they
>refuse to change it without a charge).

You can't force them to discard anything.  Caching name servers retain
information for the length of time specified in the TTL.  If you wanted
them to query the authoritative nameservers often, you should have
specified a low TTL in the records that the other servers got.

What you also need to do is get the alternate site to remove the zone from
their nameservers.  The problem is that every time a caching server queries
one of the servers, it sends back NS records with an updated
TTL, so that resets the TTL on the NS records.  As long as those TTLs keep
getting updated, the caching server will never go back to the root servers
to learn the NS records.

>incorrect info at Lucent Technology's dns server which they use for
>sending out emails to us. Our mail exchanger should not be
> and I don't want them to look up anything from
> What can I do?!

They seem to have the correct info now:

tools:~#1348% dig mx

; <<>> DiG 2.2 <<>> mx 
; (1 server found)
;; res options: init recurs defnam dnsrch
;; got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 10
;; flags: qr rd ra; Ques: 1, Ans: 4, Auth: 2, Addit: 4
;;, type = MX, class = IN

;; ANSWERS:	38672	MX	20	38672	MX	30	38672	MX	40	38672	MX	10

;; AUTHORITY RECORDS:	168271	NS	168271	NS

;; ADDITIONAL RECORDS:	81872	A	71988	A	171869	A	171353	A

;; Total query time: 17 msec
;; FROM: tools to SERVER:
;; WHEN: Tue Mar  7 17:42:28 2000
;; MSG SIZE  sent: 29  rcvd: 278

Barry Margolin, barmar at
GTE Internetworking, Powered by BBN, Burlington, MA
Please DON'T copy followups to me -- I'll assume it wasn't posted to the group.

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