I'm running Ubuntu 10.04.2 LTS Desktop. Being a web developer, naturally I created a "me.com" in my /etc/hosts file. Unfortunately, my name resolution is going out to the DNS before first checking my local hosts entry and I can't figure out why.

The end result is that if my /etc/resolv.conf contains nameserver in there first, then I get a response back in my web browser from me.com (local) within less than a second. But if I don't have that entry, then my response takes sometimes as much as 5 seconds if my ISP is a little slow.

The problem was so troublesome that I actually had to file a question here (and someone resolved it) for how to automatically insert that entry into /etc/resolv.conf. But one of the users (@shellholic) here highly recommended (and commented back and forth with me about it) that I should file this question.

Do you know why my workstation's name resolution has to hit the DNS server first before hitting my /etc/hosts file entry? For now, I'm using the resolv.conf trick.

  • 1
    You might try looking /etc/nsswitch.conf . The entries on my system are a little non-obvious, but you could test lookups with only files as an option and see if that made a difference.
    – belacqua
    Commented Mar 8, 2011 at 5:06
  • Yes, could you give us the output of cat /etc/nsswitch.conf and cat /etc/host.conf? Also: how are you testing this (through pinging, browser, packet sniffing etc)?
    – arrange
    Commented Mar 8, 2011 at 8:51
  • To complete version of @arrange, could you attach the result of time getent hosts me.com; hostname --fqdn; grep 'me.com' /etc/hosts; grep hosts /etc/nsswitch.conf; netstat -uln | grep ':53'; cat /etc/host.conf; wc -l /etc/hosts. Don't hesitate to obfuscate rationality.
    – shellholic
    Commented Mar 8, 2011 at 10:46
  • 1
    @shellholic ^rationality^rationally? heh.
    – belacqua
    Commented Mar 8, 2011 at 16:53
  • @jgbelacqua: indeed
    – shellholic
    Commented Mar 8, 2011 at 18:16

1 Answer 1


The file /etc/nsswitch.conf will let you reconfigure the order of the name resolution. By default, the host file is the first, then the configured DNS. There could be more options.

The file /etc/hosts only lists IP addresses and hostnames (multiple names for one IP if you want)

The file /etc/resolv.conf will list the default search domains, and will also list in sequence the name servers to use.

  • 5
    Also keep in mind that once a name is resolved by an application or a service on your Linux box, it will remain in cache for a duration known as the TTL (time to live). So if you switch the resolution sequence, you are better restart your system or clear any cache.
    – jfmessier
    Commented Mar 8, 2011 at 12:41
  • how do you clear the 'cache'? Commented Jan 23, 2012 at 5:48
  • I am not sure, but restarting a network connection with ifup and ifdown commands could do it. Of course, rebooting should clear the cache, but we are using Linux, right ?
    – jfmessier
    Commented Jan 27, 2012 at 17:35
  • nscd can cache name resolution queries, but does not respect ttl (and is therefore hosts caching is disabled by default). systemd-resolved will also cache entries. If none of those are configured, Linux hosts do not cache DNS responses. (Browsers likely do at the application layer though) Commented Nov 2, 2018 at 6:35

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