I am getting nowhere fast on this issue despite my searching for answers so I thought I would join and post in here as there may be some quick fix. Please understand that I have come from a more desktop/software support with some networking and server admin sort of background and am now cutting my teeth on DNS/DHCP and server admin in small to medium businesses.
I look after a site that runs MS SBS 2003 SP2 and Win XP SP2 on the desktop I believe that I have some sort of DNS issue that is causing their current problems.
At various times, users will be unable to browse the internet for a minute or two and then it will come good again all of a sudden. Additionally, there is one user in particular will start their system in the morning, they will log on and immediately after they log on will go to browse the internet and it will simply time out. In the bottom left corner will be the 'contacting site 126.96.36.199' (Google's IP add - his home page). If he then leaves this for 5-10 minutes it will suddenly start working of it's own accord. At the time the issue is happening, all internal networking appears to be fine - he can ping the server by hostname, Outlook/Exchange works happily. I will find it happens to me sporadically when I connect my laptop to their network (not joining the domain).
A few months back I changed their ISP over from a company called Dragnet - http://www.dragnet.com.au/
to Westnet. It appeared to go fairly smoothly and I don't believe this issue occurred from day one of the changeover. There were some issues with Windows security updates not having been done for a while - the handover from their previous provider (I took them over about 6 months ago) hasn't been great - and it appeared that may have been causing some issues. They are all updated now though and the problem remains.
The server is running DNS/DHCP - single network card - with the router as def gateway and all clients set to obtain IP settings automatically. An IP config on the client machine looks normal, with the DNS server and DHCP server as the SBS server and default gateway as the router. Their ISP is Westnet (I'm in Australia) and they have a static ip assigned.
What have I tried:
I have run AV/Malware scans on server/clients, after the issue began I did note that the DNS servers I had entered on the server had been left as the old ISP's DNS servers, though I don't think this should have mattered and it didn't fix anything when I changed to the new ISP's svrs. I did find this article here on EE... http://www.experts-exchange.com/Networking/Windows_Networking/NT/Q_22089445.html
but it seemed a bit different to my issue. I have checked the 'forwarders' tab in DNS as per the article and it does have the DNS servers of their ISP. I have begun reading through all the info mentioned in this article and will continue to do so however as yet I haven't struck anything that appeared to me to be something obvious to check. I have heard from various colleagues that sometimes SBS can do DNS a bit poorly but didn't know if this was true or just an inability to configure SBS DNS well.
I apologise in advance if there is some hand holding required here but I've heard great things about this site that I had to give it a go. I hope I have given enough info in this preliminary post.