I have a client site with a very strange dns issue. I used to use dyn dns internet guide but that has been shut down & I now have a monster sonicwall (nsa6600) out there. We're experiencing intermittent issues with resolving google.com, the *.google.com sites & sometimes portions of facebook. I have disconnected the router and plugged my laptop straight into the isp modem and have no problems resolving google.com, I've also troubleshooted a bit with sonicwall tech support & they couldn't find anything on the router, it's not the content filter, I've even added google.com to the white list on the content filter. I then set the dns statically on my laptop to 8.8.8.8 & it works just fine. So, it has to be an issue with the local dns servers. When it isn't working I can still ping google.com & I can also resolve google.com using nslookup. I have logged into the servers and removed the old forwarders to dyn dns internet guide, I even added google's 8.8.8.8 & 8.8.4.4 as a forwarder to both servers.
My environment:
ISP: Charter/spectrum, static ip
Router: Sonicwall nsa6600, handling dhcp, content filter
Servers:
Server 1: dell pe t630, windows server 2012 r2 standard, fsmo role holder, ad gc, pdc & dns server
Server 2: hp ml 350 g6, windows server 2008 r2 standard, ad dc, dns server
about 600 devices on the network (75 ip phones, 300 computers, 30 waps, router, 10 switches, 150 mobile devices (phones, 90 tablets, etc)
What is the maximum number of dns clients one Windows Server 2012 r2 DNS Server can serve? Is it possible we're just overwhelming these poor little dns servers with requests?
Any help would be appreciated