What happened to my dns server?

There was a problem, all pages loaded very long time, the Internet barely works, I feel that the problem with the dns. Network diagram this (user->domain controller (with dns server)->pfsense is also->Internet) the pings are normal, how to understand what's going on, any suggestions!
4 answers
July 2nd 19 at 14:29
Slow loading pages and DNS related very poorly. Doubtful sounds.
Hello, we talked with You yesterday by the way. Generally, the problem yesterday is dead switch glinkowski I haven't even thought of.
On this problem, how do I know what stage you start braking? When I turn the laptop directly to the cable provider, it is all clearly, but if via a gateway then everything is great! - nona33 commented on July 2nd 19 at 14:32
: Nicholas, I explain to avoid more questions. 1) We have not talked, you asked for help and disappeared from online, after the first response to my question. 2) When you write to a stranger - immediately call in Skype - at Onet politely )) In the end just took the time (and apparently only mine).

To understand your problem you need diagnostic. Knowing how to operate different protocols and technologies. By the way, is DNS to determine the IP destination address, this means that if you have it and slowed down, then no more than delay the definition of DNS addresses, i.e., it would result in that some sites would have been loaded at all, and some would have been loaded the first time with the brakes, and then worked quickly.

Your network, very similar, a little more than fully consists of crutches and bicycles. Change the equipment more stable, remove the soap from the corporate network. - wilfrid11 commented on July 2nd 19 at 14:35
: understood, sorry - nona33 commented on July 2nd 19 at 14:38
July 2nd 19 at 14:31
Start with nslookup ya.ru X. X. X. x, where X. X. X. x is the IP of your DNS server
Server: UnKnown

Name: ya.ru
Addresses: 2a02:6b8::3 - nona33 commented on July 2nd 19 at 14:34
Your DNS works - wilfrid11 commented on July 2nd 19 at 14:37
July 2nd 19 at 14:33
1. ipconfig /all on the client machine experiencing the problem.
Find out the list of all received DNS servers
Test for accessibility and the passage of the request ( and response speed ) as prescribed
On domain machines DNS client needs to look only to the domain controllers.
2. Look at the DNS server on the domain controller :
logs with errors\warning-s server
- availability DNS servers registered in the network connection properties of a domain controller and the request flow to them from the domain controller
- DNS settings :
the availability of root hints
availability kondishn forwarders and forwarders if you have these in the server properties.
3. Performance and no errors in Active Directory service.
July 2nd 19 at 14:35
"loop" patch cords made or routing traffic.

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