Sometimes it takes up to 30 secs to resolve the names, I'm using Firefox on OpenSuse 10.2 64 bit. No problem to ping manually any of the websites I'm trying to access.

I checked that the IPs of my ISP's Name Servers are correct in /etc/resolv.conf and I also tried to switch between the 1st and the 2nd one but with no effect.

Any other ideas?

Perhaps try using DNS servers that aren't from your ISP? Like 4.2.2.2 and 4.2.2.3.

also another approach could be to install dnsmasq or even squid so that you don't need to do so many dns lookups... i remember i had an ISP before with sucky DNS servers and installing dnsmasq locally (as in on the same desktop running firefox) made a huge difference... of course this assumes the problem is on the server side... you can confirm the problem occurs even with your firewall turned-off, right?? what kinda connection do you have?? also, what does a ping look like with your DNS servers??

Thanks to both of you for your prompt feedback, I will give a try to dnsmasq and see if it helps.

Yes the problem also occurs when my firewall is off. I have a 2.5 MB ADSL connection and I use an ECI B-Focus 312+ external modem-router.

The ping to both DNS Server looks like this:

--- 194.90.1.5 ping statistics ---
10 packets transmitted, 10 received, 0% packet loss, time 9007ms
rtt min/avg/max/mdev = 11.794/13.533/22.842/3.149 ms

--- 212.143.212.143 ping statistics ---
10 packets transmitted, 9 received, 10% packet loss, time 9019ms
rtt min/avg/max/mdev = 13.405/131.240/1068.328/331.311 ms, pipe 2

What is 4.2.2.2 / 3?

Alternatively, a friend suggested to use some DNS Root Server IPs in resolv.conf instead of my actual DNS: Do you think this could help?

do a traceroute against your dns server so you can find out where it gets slow and report the problem to your ISP with some documentation and examples over time.

4.2.2.1 to 4.2.2.6 are public DNS servers that can be used during troubleshooting to verify Internet connectivity. I use them very often, especially when I am in an unfamiliar network and would rather not use the DNS services they provide.

I just tried Dnsmask and I have to admit that it made a huge difference in 99% of the cases.

Thanks to everyone for their help.