nslookup requests time out regardless of server - ping is fine

Question

I've been having intermittent internet connection issues for a week or so now. I now suspect that these are just DNS issues rather than connection issues.

At the moment I can ping google.co.uk no problem at all (173.194.41.159) but I can't use nslookup to resolve google.co.uk (this is still running from earlier when I limited connectivity using -t. If I try it now name doesn't resolve).

My standard configuration is to use google's public DNS servers but I have tried a few others from this list: http://pcsupport.about.com/od/tipstricks/a/free-public-dns-servers.htm

I always get a

DNS request timed out
    timeout was 2 seconds

my command is:

nslookup google.co.uk 209.244.0.3

On my laptop (currently connected through my phone's 4G) this worked fine.

Web pages for ip addresses work fine and really fast through home broadband. I just can't seem to resolve any IP addresses.

Unfortunately I don't get any support from my ISP at the weekends.

Does anyone have any suggestions?

Solution

Had the same thing happening to me, able to ping external hostnames but nslookup gave nothing but the '2 second' timeouts.

In my case it turned out to be the firewall software (TinyWall). As soon as I disabled it, nslookup started working.

Comments

[Roaders]

On restarting my router I can use nslookup - for about a minute then it stops working again...

[Roaders]

Do you mean tracert? Those options aren't valid on tracert. (I am on windows 7). Thanks for your reply. I would doubt that my ISP would do anything like that sort of thing. They are Eclipse and they have never blocked, throttled or filtered anything before. It is possible though of course. I wish they had weekend support!

[Håkan Lindqvist]

@Roaders Does name resolution work if you use your ISP's nameservers? Testing that would give a pretty good hint.

[kasperd]

@Roaders I have heard of that Windows thing, but I don't use it myself, and I don't think I know anybody who really understand how it works. I hope you can find somebody else who can tell you how to find a reasonably flexible traceroute tool for Windows. I am using the default one on Ubuntu.

[Roaders]

@HåkanLindqvist I did try that vut couldn't find a listing of my ISPs DNS servers anywhere.

[kasperd]

@Roaders Every ISP I have used handed out that list of DNS servers when you request an IP address through DHCP. And every OS I know of will use that list by default. On Ubuntu you can find the list in /var/lib/dhcp, I have no idea if there is a way to find the list on Windows.

[Roaders]

Yup, but my router has Google's Public DNS servers configured for the whole network - and I can't log onto my router... At the moment I am connected directly to the modem bypassing my router and the IP for my ISPs DNS server is used when I do nslookup - it is an address that I tried earlier and it didn't work.

[Roaders]

It's beginning to look like it might be a problem with my router. I'm going to leave my laptop directly connected to the modem for a while to see if DNS stops working again.

[Larsen]

Similar cause here: F-Secure Client Security was intercepting DNS requests as I finally found in Policy Manager ("A DNS query was blocked for a domain.")