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I have DNS service from a third party, which provides an webapp for changing the DNS. I changed the DNS settings to point one of the domains I control to our new IP, but it's been hours and there was no change to the status.

Not being very familiar with how DNS changes work, I'm tring to debug what's happening - or rather not happening. I'm in the understanding that DNS takes a while to get distributed globally as caches expire, but I would like to confirm that the change has happened on my provider's DNS sever and thus that the change is underway.

The previous IP was 1.1.1.1 and the new is 2.2.2.2 (changed for this article)

First I confirmed that the domain is actually using the nameserver that I can make changes to:

ilari@alux:~$ dig mydomain.fi NS

; <<>> DiG 9.7.3 <<>> mydomain.fi NS
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 6569
;; flags: qr rd ra; QUERY: 1, ANSWER: 4, AUTHORITY: 0, ADDITIONAL: 4

;; QUESTION SECTION:
;mydomain.fi.           IN  NS

;; ANSWER SECTION:
mydomain.fi.        77916   IN  NS  dns2.myprovider.com.
mydomain.fi.        77916   IN  NS  dns3.myprovider.com.
mydomain.fi.        77916   IN  NS  dns.myprovider.com.
mydomain.fi.        77916   IN  NS  dns4.myprovider.com.

;; ADDITIONAL SECTION:
dns.myprovider.com. 1582    IN  A   10.11.12.13
dns2.myprovider.com.    1442    IN  A   10.11.12.14
dns3.myprovider.com.    1715    IN  A   10.11.12.15
dns4.myprovider.com.    1457    IN  A   10.11.12.16

(I originally used whois mydomain.fi for this, but I now realize that was not the proper way, since it doesn't actually query the DNS, only what's written about it in the whois record, if anything.)

After that, I tried using host to fetch results directly from the provider's server. I assume it should immediatly result in displaying the new IP, but instead:

ilari@alux:~$ host mydomain.fi dns.myprovider.com
Using domain server:
Name: dns.myprovider.com
Address: 10.11.12.13#53
Aliases: 

mydomain.fi has address 1.1.1.1

This was after many hours. I thought it should have changed to 2.2.2.2 immediately since it should query the exact server I'm making changes to from the web interface. What should I expect to see as results?

How do I make sure the web interface at my provider has worked, and the DNS has changed properly at their server?

It turns out this was a problem at their end. The web interface hadn't made the change properly, and the IP wasn't actually changed at their DNS server.

After their problem was solved, there was still a few minutes delay after the change was seen with host mydomain.fi dns.myprovider.com (and of course longer until the change is seen globally).

Ilari Kajaste
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3 Answers3

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A DNS change is "active" as soon as you make it and verify that all of the authoritative servers (as listed in the zone's NS records) are serving the new record. Ladadadada pointed you at a question/answer that explains how to check this.

A DNS change is "propagated" once the caches on all servers around the world have expired and they've retrieved the new information from the authoritative servers. ("propagation" is technically the wrong word - it's actually cache expiration - but it's the commonly used term).

You can control the first of these. You cannot control the second (the TTL (Time To Live) value on the record should theoretically limit how long it takes for caches to expire, however there are ISPs out there that simply don't respect TTL values -- AOL in particular is notorious for this).

Community
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voretaq7
  • 80,749
1

What's the time to live (TTL) setting for the mydomain.fi record? If the TTL is, say, one day, you would not see changes until tomorrow.

cjc
  • 25,492
0

I like to use dig to check this:

dig hostname.to.check @dns.myprovider.com

Make sure to check all of the nameservers to see that they all respond with the same.

Squish.net also has a great tool for DNS traversal and it will tell you how the active nameservers are going to respond to your request.

Dave Drager
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