I have Ubuntu Server 11.10 64-bit . Updates were working but now fails every time after apt-get update [duplicate]

Question

Possible Duplicate:
apt-get update fails to fetch files, “Temporary failure resolving …” error

This is what I get when I try to run apt-get update

Err http: //security.ubuntu.com oneiric-security InRelease                   

Err http: //us.archive.ubuntu.com oneiric InRelease                          

Err http: //security.ubuntu.com oneiric-security Release.gpg                 
  Temporary failure resolving 'security.ubuntu.com'
Err http: //us.archive.ubuntu.com oneiric-updates InRelease                  

Err http: //us.archive.ubuntu.com oneiric Release.gpg
  Temporary failure resolving 'us.archive.ubuntu.com'
Err http: //us.archive.ubuntu.com oneiric-updates Release.gpg
  Temporary failure resolving 'us.archive.ubuntu.com'
Reading package lists... Done           
W: Failed to fetch http: //us.archive.ubuntu.com/ubuntu/dists/oneiric/InRelease  

W: Failed to fetch http: //us.archive.ubuntu.com/ubuntu/dists/oneiric-updates/InRelease  

W: Failed to fetch http: //security.ubuntu.com/ubuntu/dists/oneiric-security/InRelease  

W: Failed to fetch http: //security.ubuntu.com/ubuntu/dists/oneiric-security/Release.gpg  Temporary failure resolving 'security.ubuntu.com'

W: Failed to fetch http: //us.archive.ubuntu.com/ubuntu/dists/oneiric/Release.gpg  Temporary failure resolving 'us.archive.ubuntu.com'

W: Failed to fetch http: //us.archive.ubuntu.com/ubuntu/dists/oneiric-updates/Release.gpg  Temporary failure resolving 'us.archive.ubuntu.com'

W: Some index files failed to download. They have been ignored, or old ones used instead.

Answer 1

This looks like DNS failure, possibly not directly related to the distribution's update mechanism. Can you resolve security.ubuntu.com and us.archive.ubuntu.com? Try:

nslookup security.ubuntu.com
nslookup us.archive.ubuntu.com

I see that some of the files that are reported as "Failed to fetch" are now available.