What can be done if a certain site does not open from the provider's network?

Question

Domain Name System

It so happened that I work in a small local provider with a grid for 1000 physicists and 200 legal experts. Knowledge is almost zero, there was a problem (fortunately, so far the subscribers have not contacted, I noticed it myself) with access to https://help.keenetic.com/ . The RTK highway, with the RTK (albeit in other regions, I couldn’t find anyone to look at here) there is access to the site. From mobile MegaFon I go there without problems. In nslookup the answer is normal. It can be seen that this is some kind of help on the zendesk domain. I can’t go to help.zendesk.com either, although everything is OK with zendesk.com. With resources like keenetic.ru, forum.keenetic.ru and others, this is not observed. In general, I no longer encountered problems with access to anything other than this help.zendesk

Replacing DNS on the router/computer does nothing. The resource is pinged, the output in the browser is:

It does not depend on the device. I tried it on a work PC connected directly to the access switch, I tried it on my home PC with a router. Tried from smartphone. There is no access from my network. I have access to the gateway, switches, kernel and servers. Gateway CCR1036. I can’t formulate my question adequately for Google, nothing related to my requests is being searched. I ask for help in enlightening the network lamer, there is no one above me now, only I can deal with this.

Tracing:


Addition: Using Tor, the site opens.

Answer 1

The keenetic.zendesk.com address is the real address of the server hosting the help.keenetic.com website , which is what it reports nslookup. By the way, if you do it chcp 1250, it will nslookupspeak in an English voice.
But why this site is not available from your address is much more difficult to say, you need to track the entire chain. By the way, CloudFlare servers are involved in this chain, maybe it's because of them?
You can try to exclude browsers from the problem by checking with the command:
telnet help.keenetic.com 80
If the connection happens and the screen clears, this is already good, then there is a physical connection. Then copy-paste the following into the empty window:

GET http://help.keenetic.com/ HTTP/1.0
Host: help.keenetic.com

And you need to insert all 3 lines, two with text and one empty. This is an analogue of the request that browsers send. If everything is in order, an HTTP server response will appear about redirecting to the address https://help.keenetic.com/hc, and therefore the browser or some kind of proxy server is to blame.
And if it’s not in order, or the connection just didn’t start, it means that traffic is being cut somewhere, you need to look ...

Answer 2

The question is closed. I don’t know what happened, but as a result of a long-term power outage after the storms, the backup power was not enough and all the servers went into poweroffs. After turning on the light, I accidentally discovered that there is access to all sites on zendeske. No idea what it was, I decided to unsubscribe just in case. Suddenly someone will look.