I have a starnge problem here with my Ubuntu 10.04 LTS server.
When I try to update the server I got messages Err and warning, here an eg:
sudo apt-get update 

Err http://fr.archive.ubuntu.com lucid Release.gpg

W: Impossible de récupérer http://security.ubuntu.com/ubuntu/dists/lucid-security/multiverse/i18n/Translation-fr.bz2  Erreur temporaire de résolution de «*security.ubuntu.com*»

but my server is connected and if I try to ping some DNS server (eg: ) it works !

Can some one help me on that issue ?