DNSStuff.com...can't even show what IP a hostname resolves to?!

[Ichinisan]

Summary: It seems that DNSStuff.com can't show the most basic info about a hostname: WHAT IP DOES IT RESOLVE TO?!



I work for a small local ISP. A customer called us yesterday and said their employees can access http://webmail.us.yokogawa.com/ from home, but not from work.

I tried from my workstation and the page failed to load.
I connected remotely to my home computer and the page worked (prompted for a password).

I pinged from both places and saw that the hostname resolved to different IPs:
216.130.151.232 (Works, resolved from cable modem network)
65.203.111.18 (Fails, resolved from workstation)

I tried the web address from my iPhone with WiFi disabled, and it failed...so I assume AT&T's network resolves th 65.203.111.18 address

So, I assume there is a DNS problem and most systems will resolve the 65.203.111.18 address. Yokogawa employees are local and they have our cable modem Internet service at home, so that's why they reported that it worked from home. I'm sure employees with other ISPs would not be able to load the page.

A 216.130.x.x address looks like one that we host, so the server is either 1) in our head-end or 2) operated by Yokogawa on our fiber network.

I asked the CSR to advise the customer: They may need to update DNS on their end because only our customers can resolve the correct address...and it's probably a fluke that allows those to resolve the old / correct address.

Because the hostname resolves differently on different parts of our network, I created a ticket yesterday with our network engineers. I suspected that forcing the DNS update might cause even the CM customers to lose access. This morning, there was no response to my open ticket, but SOMETHING changed. It now works from my workstation and resolves to 216.130.151.232.

I want to know what outside networks see when they try to resolve webmail.us.yokogawa.com, so I ran the "PING" app on my iPhone and verified that AT&T's network still resolves the non-working address (65.203.111.18). Still, I wanted to see how it resolves on a network other than AT&T. That's when I found out that DNSStuff.com doesn't show this most basic bit of information about a hostname. What the hell?!

Since I started writing this post, I ran the PING app on my iPhone again and got the working 216.130.151.232 address, so it seems to have updated just now.

Now I'm all confused.

 

[Fardringle]

It resolves to 216.130.151.232 for me on Comcast in Salt Lake City, UT.

Did they recently change the address (or hosting location) of the server? If so, the various ISP DNS servers might still be in the process of updating their records to the new address. This would explain why your AT&T phone did not work earlier but does work now.

 

[drebo]

nslookup is what I use, usually.

 

[VinylxScratches]

Isn't there a TTL on DNS updates? Some are 24 hours, some are 5 minutes etc....

 

[her209]

It takes time for DNS cache entries to time out. See DNS propagation.

 

[Ichinisan]

It resolves to 216.130.151.232 for me on Comcast in Salt Lake City, UT.

Did they recently change the address (or hosting location) of the server? If so, the various ISP DNS servers might still be in the process of updating their records to the new address. This would explain why your AT&T phone did not work earlier but does work now.

I suspect that our network guys made the fix without telling me. I think they looked at my ticket this morning. If there was some way to have DNSStuff.com show that they think the IP is, it doesn't matter now (it's too late to know which one would have resolved yesterday).

nslookup is what I use, usually.

Yeah...but you have to specify the nameserver to use. I think most ISPs only allow their subscribers to access the nameservers. I wanted to see what a third-party NS would return. You'd think DNSStuff.com would at least tell you what their NS returns. It's pretty strange to me that they wouldn't at least tell you what they think the IP is. That would be useful for some mobile phones that have a web browser, and no other way to easily find the IP.

A domain name is attached to a limited amount of information. The current registered IP is one of the more useful details. Why would their site leave that out? /rant

It takes time for DNS cache entries to time out. See DNS propagation.

I know this. I was just trying to figure out what changed. I'm pretty sure they always had the 216.130.151.232 address and it briefly changed to 65.203.111.18 due to some oversight. Then, it would have propagated everywhere except to part of our internal network because the NS was "authoritative" and never looked for updates. The AT&T test seemed to confirm this...but I'd need to try at least one more outside NS.

Just a theory. Too late to confirm now because someone fixed something...somewhere.

 

[Emulex]

intodns.com is the new dnsstuff.com

 

[mxnerd]

Seems intodns.com does not check subdomain

found another useful site http://www.keyhints.com/

their DNS tracing site dntrace.keyhints.com

 

[Fardringle]

There are some interesting tools on that Keyhints.com site. However, I'm curious to find out who they use as their DNS authority since their DNS lookup tool reports the old (invalid) IP address for the mailserver listed in Ichinisan's post. It also shows an old (invalid) IP address for one of my clients that moved to a new mail server 7 days ago.