Did you try and call BT they should be able to help you but try to get some one to help you from the UK and from India , the people from India are no good
Does the error occur on all of the websites you are visiting? Or just some sites in particular? Are they secured sites like bank sites and others that deals with money matters? If so, it is not the problem with the server. Something needs to be adjusted either in your computer or your router, if you are using one.
If you get that error its cause of the BT DNS and nothing else , they much be having a problem with a breakage in connection . I am sure it is working fine today
Personally I dont think its to do with the BT DNS, however if you want to try give OpenDNS a go. I use it at home and found it to be pretty reliable, it also warns of phishing sites.
I now use OpenDNS as my primary DNS with my ISP DNS as a backup.
404 Errors come from the server, which means the page on that particular server can't be found - it's unlikely that it's a DNS problem, more likely a problem with the particular site you're accessing.
There's a slim chance the DNS is pointing to the wrong site, but it's unlikely in my opinion.
saubryn is right, 404 errors are produced by Apache in webservers. What website URLs did you try?
Try Google, it is the most reliable site ever made, so if it doesnt load, something is wrong
Yep those errors are server errors. If you are getting them all the time you need to see if you can visit any other sites than those you are trying if not you need to check your settings to make sure that something is not checked that should not be, etc.