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I need to override the name resolution for a given domain name for testing purposes in my browser (Firefox) on Ubuntu, so that when I write "", it will point to a given IP that I decide, instead of resolving via DNS.

I already tried editing the /etc/hosts file, but it doesn't work. It does work when I ping the domain from the terminal, but Firefox seems to ignore it. I also flushed and disabled Firefox's DNS cache with no luck. It seems Firefox simply does not look at /etc/hosts and always resolves the domain name by asking the DNS.

What am I missing?

I've found similar questions like "how do I override DNS in Firefox" to which the usual answer is "use /etc/hosts", then the poster usually replies "I don't want to use /etc/hosts for this or that reason" - well I would be perfectly fine with using /etc/hosts but what nobody says is it just doesn't work for Firefox...

Thanks m.

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Can you provide a link to your hosts file with pastie? – evan.bovie Jun 1 '11 at 15:43
My problem seems to be related to some sort of DNS cache. After rebooting, the changes I had made to /etc/hosts finally took effect on Firefox and other browsers. – matteo Jun 1 '11 at 19:30
Now I've changed /etc/hosts again and the browsers still "uses" the previous version. Now even after rebooting I cannot get the browser to see the changes I've made to /etc/hosts. – matteo Jun 1 '11 at 19:30
Note that the issue affects all browsers, not only firefox, but not other programs: ping and wget always resolve names correctly according to /etc/hosts. – matteo Jun 1 '11 at 19:31
I have already tried /etc/init.d/dns-clean, I've already tried disabling dns cache in Firefox both with the DNS Cache addon and manually in about:config. No way. – matteo Jun 1 '11 at 19:31

There is a post at azcentral. It says you need to enter two keys in about:config, namely

  1. "network.dnsCacheExpiration"
  2. "network.dnsCacheEntries"

and set them to 0.

Give it a try. I have not, but your question seems still unanswered.

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