DHCP best practice

[kenrick]

We don't always need to restart both servers, sometimes only one. This varies too which server needs restarting.

[LytchettNM]

So if you not losing IP connectivity to the site and google during the time when you can't access the site it would seem to be a transport issue, how do you manage you traffic? Normal or invisible proxy via a local firewall or server?

I would double check the devices you have given static IP's to just to make sure something has not been given the same IP then double check how you have you switching setup to check for a loop, I have also seen a NIC fail where it would flood the network with network traffic, overloading the CPU on the local onsite router looked like a loop but was not and had to be connected to the dhcp server for about 3 minutes before it started sending packets.....took a little time to find having to unplug each edge switch from the core for 5 mins.

If you can unplug all edge switches and then just plug in 1 at a time to see when the problem occurs.

You could run up wire shark this will allow you to see what's happening within the network.

How often is this happening?

[kenrick]

Our DNS points to Google, although clients go to our own servers first. If I set DNS statically and have primary DNS set locally and then secondary straight to Google the problem still exists.

PCs do not lose network connection at any point which is why I don't think it has anything to do with DHCP.

[Davit2005]

Hello,

 

We are having problems with our internet dropping out randomly and pages having to be refreshed. We have created two new DNS Servers but the problem still exists. Occasionally we lose internet all together and we have to physically restart the servers to get internet back, restarting DNS services doesn't work.

 

Senior management suggested it might be DHCP but cannot see why. He also mentioned that DNS and DHCP shouldn't be on the same server. What is the current best practice for DNS and DHCP?

 

Many thanks

 

Paul

 

Another +1 for DHCP, DNS and AD DS on same servers.

 

Issues with DNS are going to give more than intermittent Internet loss unless as others have said and it is forwarders.

 

Run DCDIAG DNS tests, check for replication issues.

 

How about installing PRTG or something similar to check DNS not only of your internal servers but external revolvers. Check clients event logs for DNS related issues.

[JackCPickup]

When connection is down, what result do you get from setting DNS statically on an affected PC to your external DNS? Is your proxy seamless or do you rely on a wpad.dat or .pac file on the server?

 

When it's down, are you able to tracert externally from the server?

[kenrick]

Quick question, i have just updated my root hints. If i tick the box to use these when there are no forwarders, is it safe to delete the forwarders from both dns servers? I am using Google; 8.8.8.8 and 8.8.4.4

 

Thank you

[LytchettNM]

It's your Choice as to if you use root hints or forwards so deleting the forwards won't stop your DNS from working, personally I would recommend using forwards to your ISP's DNS service.

If you only use root hints then for every request that's outside of you DNS's root zone the DNS service will have to hint for part of the request i.e. If http://www.bbc.co.uk first request will be for ".uk" then when this is returned another request for ".co" and then "BBC" before the browser can send the request to the site the user asked for.

There is a TTL on every response and your local DNS service will cache the request for the duration of that TTL then it all starts again, the hope would be that your ISP's DNS service will already have most stuff cached and already have done the lookup which means that the request that comes from your network will resolve with just the one lookup request.

I hope this helps to make it a little clearer [emoji848]