One week ago, my hosting provider moved to another server and changed the IP address from 78.46.237.174 to 78.47.120.47. Obviously, everything was prepared fine, even the TTL handling.
Okay, I understand that updating the ISP provider’s DNSses worldwide could take up to 24 hours and at the end of the day this cannot be done real time. Yesterday, I tried to call up my domain marco-steinhaeuser.de in several browsers and operating systems and failed with a timeout. Only a few times the page was loading properly. Checking the host of the domain with $ host marco-steinhaeuser.de, sometimes the old IP-address appeared, sometimes the new one. What the hell is going on here?
Linux doesn’t cache the DNS by default, on Windows you had to enter $ ipconfig /flushdns on your command line to clean your DNS cache. After clearing the router’s DNS cache as well (a simple reboot did it), the same behavior appeared, this way I excluded the problem on my site. Alright, next step:
$ whois marco-steinhaeuser
gives you a clear idea which Domain Name Servers (DNS) are used by the hosting provider and if the IP change was ended up finally at your country’s NIC. The result is:
Domain: marco-steinhaeuser.de
Domain-Ace: marco-steinhaeuser.de
Nserver: ns1.scunc.it
Nserver: ns2.scunc.it
Which looks nice from my hosting provider’s site. Just let’s go ahead with looking up which entry was made for marco-steinhaeuser.de on the name servers ns1.scunc.it and ns2.scunc.it. First of all, call nslookup on your command line:
$ nslookup
Now, “nslookup” the server you want to inspect:
> server ns1.scunc.it
Default server: ns1.scunc.it
Address: 81.169.185.80#53
> set type=a
> marco-steinhaeuser.de
Server: ns1.scunc.it
Address: 81.169.185.80#53
Name: marco-steinhaeuser.de
Address: 78.47.120.47
and
> server ns2.scunc.it
Default server: ns2.scunc.it
Address: 85.10.239.34#53
> set type=a
> marco-steinhaeuser.de
Server: ns2.scunc.it
Address: 85.10.239.34#53
Name: marco-steinhaeuser.de
Address: 78.47.120.47
Alright buddy, that looks okay as well: The entries for the new IP address on both DNSses on your hosting provider’s site seem to be correct. The next step shall be to check your ISP’s name server. You shall find that information at your router as it is entered automatically by default.
In my case (Kabeldeutschland) I had to nslookup 83.169.186.33 as well as it’s alternative 83.169.186.97. Are you still in nslookup mode on your console? Here we go:
> server 83.169.186.33
Default server: 83.169.186.33
Address: 83.169.186.33#53
> set type=a
> marco-steinhaeuser.de
Server: 83.169.186.33
Address: 83.169.186.33#53
Non-authoritative answer:
Name: marco-steinhaeuser.de
Address: 78.47.120.47
Wow! The new IP address is updated at least at the primary name server! But look at this one:
> server 83.169.186.97
Default server: 83.169.186.97
Address: 83.169.186.97#53
> set type=a
> marco-steinhaeuser.de
Server: 83.169.186.97
Address: 83.169.186.97#53
Non-authoritative answer:
Name: marco-steinhaeuser.de
Address: 78.46.237.174
Whatever the “Non-authoritative answer” should mean: Obviously both official Kabeldeutschland DNS servers are not synchronized. That’s a clear server misconfiguration and misbehavior in my opinion. To be honest: How the hell that can happen to a certain ISP?
However, to fix your problem, just turn off the alternative name server in your router.
No probs at all, shit can happen. So I called the 0-800 hotline to tell them what they did wrong. In the moment it was over the head of that 1st line guy and he could not help me seing my cable modem online or whatever, he tried to delegate me to another telephone number with massive costs (95 ct per minute). Unfortunately, he was not able to assign a ticket to a 2nd line. Service looks different, doesn’t it?
Of course, I would never call this hilarious number to tell them _their_ problems. Also, it doesn’t make sense to bother the server owner you would find on ripe.net as he has probably different stuff to do. Instead, I wrote all the details and logs he would need to 
who is the Zone-C of kabeldeutschland.de. Of course, I didn’t get any reply yet, let’s see whether something happens at all…
Many thanks to my mate Thorsten who helped me sorting this out!
