Does RDP use DNS after connection has been made

Question

We are experiencing network drops on our (small) company network. The computers are all connected wired and the drops seem to be internal and external.

We have a simple DNS installed on our PC's for a loop back for addresses like lc.* to develop multiple websites without needed to change the host file for each url. There is no caching on this server and other request are forwarded to our providers DNS. This works as I can connect to all websites/services without any delay.

But mostly when using a RDP connection I get regular timeouts and after a few seconds it connects again. This happens when I'm at work and connect to external servers, or when i'm working offsite and connect to my work computer.

We hired somebody to check the network and he says the timeouts are because of the DNS server. He even says most slow network problems are because of DNS issues, which I can understand if the initial connection is slow. His advice is to use a direct IP instead of a host name, to solve the drops.

But as far as I know, once a connection has been made, the DNS server is no longer used. And when I connect from offsite to my work computer, it doesn't matter at all what DNS my work computer uses.

Could a DNS setting cause network drops after the connection has been made? Or is it indeed no longer used once we know example.com can be found at 93.184.216.34?

Answer 1

I agree that his answer is suspect, and RDP would not require multiple lokups - as you pointed out, DNS issues would slow down the initial connection only. An RDP connection requires nothing more then a single tcp connection.

To say most network slowdowns are caused by DNS would seem wrong - ISP congestion, routing loops, WIFI interference and to many devices for a router to handle are all likely reasons for slow Internet (in general) as are DHCP issues.

Without more knowledge of your network configuration it almost sounds like a DHCP issue - I'd be inclined to set a static IP outside the DNS range for my desktop and see if the problem goes away. If that did not work I'd also look to see the amount of traffic on the network, and see if it's being flooded with connections/Mac addresses. (Also, Is WIFI involved?)