DNS issue... need help

[Stu]

Since I moved to Virgin from Sky ADSL, browsing on my main PC has become really slow, with "resolving host" constantly in the bottom corner of Chrome. I've cleared the DNS cache in Chrome via chrome://net-internals/#dns, and I've cleared the Windows cache using ipconfig /flushdns, but it hasn't made a difference.

Further investigation, I noticed that the problem only happens when my server is on... if I turn off the server, then browsing on my main desktop PC is fast. Running ipconfig with the server is on versus off shows different values in "DNS Servers"...

When the server is on, "DNS Servers" = 192.168.0.40
When the server is off, "DNS Servers" = 194.168.4.100, 194.168.8.100

My server's IP is 192.168.0.40; whereas I believe the default Virgin servers are (Primary) 194.168.4.100 and (Secondary) 194.168.8.100.

I don't know much about network routing, but it appears to me that my desktop PC is routing via my server when the server is on... how do I fix this?

 

[BigT]

A bad quick and dirty way of fixing it is to give your desktop a fixed IP address together with the correct gateway and ISP DNS servers.

That doesn't find the root cause and fix it properly though. What OS is your server? And what are it's IP configuration settings?

Given the default gateway and DHCP server are listed as the same in both scenrios at 192.168.0.1 (presumably your router) then the only way I can think of this happening is that your Virgin router has your server listed as it's first port of call for DNS ahead of the ISPs. If its on it uses it and if it is not then it goes out to the ISP.

 

[skyripper]

Have you got DHCP running on your Router, and DHCP running on your server as well?

 

[SupraWez]

Bin those DNS server entries and point them to something else, google for example is 8.8.8.8 and 8.8.4.4 or OpenDNS https://www.opendns.com/home-internet-security/

If your that way inclined you could fire up your own DNS server, not really worth it these days unless you have a specific need or security concern.

 

[Stu]

I think the issue is my desktop PC, because phones and tablets don't have any issues.

 

[Stu]

I have everything default in Windows... Windows 10 on desktop and Server 12 Essentials. I haven't manually set anything regarding DNS.

 

[Stu]

Have you got DHCP running on your Router, and DHCP running on your server as well?

DHCP is on router, but not server. I haven't changed anything on main PC or server, only changed ISP. Everything was good before.

 

[Stu]

Think I've found the issue... followed these instructions to set DNS manually, and found it was set to point to my server. No idea how that happened!!! Thanks guys.

 

[BigT]

Think I've found the issue... followed these instructions to set DNS manually, and found it was set to point to my server. No idea how that happened!!! Thanks guys.

That would definitely have given you the experience you observed. although strange how it didn't happen with a previous ISP.

 

[neil_g]

Bin those DNS server entries and point them to something else, google for example is 8.8.8.8 and 8.8.4.4 or OpenDNS https://www.opendns.com/home-internet-security/

If your that way inclined you could fire up your own DNS server, not really worth it these days unless you have a specific need or security concern.

People always say to use google, but they're actually pretty bad for anything needing reliable geolocation. You don't always get a good nearby server from the pool either.

If your isp one really does suck for some reason then find a different UK based one. Otherwise Google should be limited to testing only.

 

[neil_g]

Incidentally I think the 194.168.4.100 dns only get issued with the vm box in modem mode? Pretty sure in router mode the dhcp default from memory is the routers own IP?