DNS Troubleshooting: where to begin?

[gatorback]

Any diagnostic questions or actionable suggested remedies are appreciated. Is there a DNS setting in the router that should be checked / toggled?

All devices (Win7, XP, IOS) failed to return the target website. Website support indicated site is working, so I switched the iPad from Wifi to Cellular and the website was returned. Concluded problem is on my end and not website

Other observations regarding target website (www.coned.com):

* ping response (DOS command): "Ping request could not find host coned.com."
* nslookup from RT-AC68U router

username@ECHO:/tmp/home/root# nslookup coned.com
Server: 127.0.0.1
Address 1: 127.0.0.1 localhost.localdomain
Name: coned.com
Address 1: 158.57.169.31 wsfp1k.coned.com
Address 2: 158.57.189.31 coned.com

username@ECHO:/tmp/home/root# ping -c 3 coned.com
PING coned.com (158.57.189.31): 56 data bytes
--- coned.com ping statistics ---
3 packets transmitted, 0 packets received, 100% packet loss​

* http://158.57.169.31/ returns the ConEd website
* All device network adapters are DHCP configured.
* Merlin 378.55 on a RT-AC68U

 

[RMerlin]

Something seems wrong with that domain. Its four authoritative nameservers return www.gslbext.coned.com as the cname for www.coned.com, but those same authoritative server don't return anything when trying to resolve that CNAME - it only works if I try to resolve it on another nameserver. I suspect the issue is on the domain's end itself, not you (or me).

[root@babylon2 ~]# nslookup www.gslbext.coned.com ns4.coned.com
Server:     ns4.coned.com
Address:   158.57.167.88#53

Non-authoritative answer:
*** Can't find www.gslbext.coned.com: No answer

Also note that we get different results on www.coned.com. Here's what you get when querying their authoritative nameservers:

[root@babylon2 ~]# nslookup - ns1.coned.com
> www.coned.com
Server:     ns1.coned.com
Address:   158.57.168.8#53

www.coned.com   canonical name = www.gslbext.coned.com.

 

[gatorback]

@RMerlin: Thank you for responding. My understanding of DNS is limited to: a URL (hierarchical text string) is resolved to an IP address. This can be manually done with the nslookup command to verify that the string is resolved to an IP. I put the IP (158.57.189.31) into the web browser and the website is returned:

http://158.57.189.31
​

A few questions please:

1) What command did you invoke to return www.gslbext.coned.com?
2) Does ns1 in ns1.coned.com indicate a nameserver \ DNS machine?
3) Why did you pre-pend ns1 to coned.com? How does having the target's local DNS IP help?
4) If the cellular connected iPad is able to properly access the site via www.coned.com, isn't the problem on my end?
​

Pinging coned.com from the router command-line does properly resolve, but there is no reply indication:

user@ECHO:/tmp/home/root# ping coned.com
PING coned.com (158.57.189.31): 56 data bytes

Strange: DOS command line does not indicate resolving coned.com => 158..57.189.31

 

[RMerlin]

First, you will have to determine if the site you want to access is coned.com or www.coned.com. Those are two totally different things. You mention trying to access www.coned.com, but you did all your tests using coned.com instead.

Explaining how the DNS system works is unfortunately beyond what I'd be willing to write here (it's a bit complicated and requires a lot of explanations). Basically, there is a problem with the way whoever manages the coned.com domain has configured things out in their DNS - not much you can do on your end. It will randomly work or fail for people.