Super-Networking Blog

Well you come in and your Internet is slow across the board, doesn’t matter what website you are going to. Being an IT Professional and in my case the Network Admin I know I will hear about it. It is time to start checking it out even if it is just my PC.

First think I look at is there anything down, check Solarwinds Orion and everything is up, no events and everthing has been pretty quiet. Next I check for bandwidth, are we maxing out any of our links or Internet connections, answer no. Everything appears to be working, no errors, pings appear to be normal to outside world.

One thing a lot of people overlook, check your DNS server forwarders. A lot of the time in a Microsoft environment your PC will point to the Domain Controller which is running DNS and all of your DNS queries both internal and external will run through those servers. If you don’t want to deal with having your DCs connect directly to the DNS root servers, which can be a pain, you add in your ISP DNS servers as DNS query forwarders.

So try pinging all of your DNS forwarders and see if all of them are reachable, if one is down remove it from the list. I recommend having at least 3 of the in your list if possible. Even if they do respond to pings but are losing packets you don’t want to use them, DNS queries slow way down with packet loss. Hopefully you will find one that is having issues, you remove it and everything is working great.

This is by no means all the things that can go wrong or all the things you can check into but is a good high level start to troubleshooting this problem.