DNS / Network issues on new network – where to start? Ipv6 issue?
Posted on 2011-10-07
A new network we installed is having problems and I need some input.
DNS resolution seems to be failing. E.g. Slow internet page loads and various other issues.
For historical reasons there is the following setup. One physical network. Has one WAN / Broadband connected served by a Draytek 2830 router which gives out DHCP on a range of 192.168.5.X. This serves general visitors and the wireless users not connected to domain.
Also there is another WAN / Broadband connection served by another Draytek 2830 (just put in by us). This is on a static range of IP on the subnet 172.168.6.X. Therefore the second 2830 does not have DHCP enabled and on this subnet is a new Windows 2008 server we put in and 10 workstations. They all have static IP’s
Users were complaining of slow internet, but not always. But we witnessed it at times. E.g. Google taking 30 seconds to load. Some images on pages not downloading
If we changed the DNS on a workstation to be Google DNS directly (rather than that of the server on the network) it immediately solved the issues on that PC. Although we had one issue where having Google DNS on a workstation meant that user could not get onto online banking, so had to change back to local server DNS and then they could.
It’s been an issue for a week and when I think I have solved it because it can behave OK it rears its head again
1 ) What free tools can I use to try and establish what is happened? I’ve never used any network monitoring tools but I believe there are free ones which could see what traffic is going over it.
2 ) I’ve looked on the Event viewer for DNS and although some 5501 - DNS_EVENT_BAD_PACKET_LENGTH events as “information” (not an error or warning) over the past few days (maybe this is an indication) I can’t see anything else unusual.
3 ) A colleague suggested disabling IPv6 on the workstations because he noted that some of the PC’s had open sessions on the server using IPv6 IP rather than an IPv4. Could there be something in this?
4 ) IS there anything else anyone can suggest as to how I should go about resolving this problem. I really want to have a weekend.