Hello,
I have a strange problem with apt-get.
I run "sudo apt-get update" and get the errors:

Code:
Err http://kr.archive.ubuntu.com karmic Release.gpg                         
  Could not resolve 'kr.archive.ubuntu.com'
Err http://kr.archive.ubuntu.com karmic/main Translation-en_US              
  Could not resolve 'kr.archive.ubuntu.com'
Err http://kr.archive.ubuntu.com karmic/restricted Translation-en_US
  Could not resolve 'kr.archive.ubuntu.com'
Err http://kr.archive.ubuntu.com karmic/universe Translation-en_US
  Could not resolve 'kr.archive.ubuntu.com'
Err http://kr.archive.ubuntu.com karmic/multiverse Translation-en_US
  Could not resolve 'kr.archive.ubuntu.com'
Err http://kr.archive.ubuntu.com karmic-updates Release.gpg
  Could not resolve 'kr.archive.ubuntu.com'
Err http://kr.archive.ubuntu.com karmic-updates/main Translation-en_US
  Could not resolve 'kr.archive.ubuntu.com'
Err http://kr.archive.ubuntu.com karmic-updates/restricted Translation-en_US
  Could not resolve 'kr.archive.ubuntu.com'
Err http://kr.archive.ubuntu.com karmic-updates/universe Translation-en_US
  Could not resolve 'kr.archive.ubuntu.com'
Err http://kr.archive.ubuntu.com karmic-updates/multiverse Translation-en_US
  Could not resolve 'kr.archive.ubuntu.com'
Err http://security.ubuntu.com karmic-security Release.gpg
  Could not resolve 'security.ubuntu.com'
Err http://security.ubuntu.com karmic-security/main Translation-en_US
  Could not resolve 'security.ubuntu.com'
Err http://security.ubuntu.com karmic-security/restricted Translation-en_US
  Could not resolve 'security.ubuntu.com'
Err http://security.ubuntu.com karmic-security/universe Translation-en_US
  Could not resolve 'security.ubuntu.com'
Err http://security.ubuntu.com karmic-security/multiverse Translation-en_US
  Could not resolve 'security.ubuntu.com'
Reading package lists... Done
W: Failed to fetch http://kr.archive.ubuntu.com/ubuntu/dists/karmic/Release.gpg  Could not resolve 'kr.archive.u
buntu.com'

W: Failed to fetch http://kr.archive.ubuntu.com/ubuntu/dists/karmic/main/i18n/Translation-en_US.bz2  Could not r
esolve 'kr.archive.ubuntu.com'

W: Failed to fetch http://kr.archive.ubuntu.com/ubuntu/dists/karmic/restricted/i18n/Translation-en_US.bz2  Could
 not resolve 'kr.archive.ubuntu.com'

W: Failed to fetch http://kr.archive.ubuntu.com/ubuntu/dists/karmic/universe/i18n/Translation-en_US.bz2  Could n
ot resolve 'kr.archive.ubuntu.com'

W: Failed to fetch http://kr.archive.ubuntu.com/ubuntu/dists/karmic/multiverse/i18n/Translation-en_US.bz2  Could
 not resolve 'kr.archive.ubuntu.com'

W: Failed to fetch http://kr.archive.ubuntu.com/ubuntu/dists/karmic-updates/Release.gpg  Could not resolve 'kr.a
rchive.ubuntu.com'

W: Failed to fetch http://kr.archive.ubuntu.com/ubuntu/dists/karmic-updates/main/i18n/Translation-en_US.bz2  Cou
ld not resolve 'kr.archive.ubuntu.com'

W: Failed to fetch http://kr.archive.ubuntu.com/ubuntu/dists/karmic-updates/restricted/i18n/Translation-en_US.bz
2  Could not resolve 'kr.archive.ubuntu.com'

W: Failed to fetch http://kr.archive.ubuntu.com/ubuntu/dists/karmic-updates/universe/i18n/Translation-en_US.bz2 
 Could not resolve 'kr.archive.ubuntu.com'

W: Failed to fetch http://kr.archive.ubuntu.com/ubuntu/dists/karmic-updates/multiverse/i18n/Translation-en_US.bz
2  Could not resolve 'kr.archive.ubuntu.com'

W: Failed to fetch http://security.ubuntu.com/ubuntu/dists/karmic-security/Release.gpg  Could not resolve 'secur
ity.ubuntu.com'

W: Failed to fetch http://security.ubuntu.com/ubuntu/dists/karmic-security/main/i18n/Translation-en_US.bz2  Coul
d not resolve 'security.ubuntu.com'

W: Failed to fetch http://security.ubuntu.com/ubuntu/dists/karmic-security/restricted/i18n/Translation-en_US.bz2
  Could not resolve 'security.ubuntu.com'

W: Failed to fetch http://security.ubuntu.com/ubuntu/dists/karmic-security/universe/i18n/Translation-en_US.bz2  
Could not resolve 'security.ubuntu.com'

W: Failed to fetch http://security.ubuntu.com/ubuntu/dists/karmic-security/multiverse/i18n/Translation-en_US.bz2
  Could not resolve 'security.ubuntu.com'

W: Some index files failed to download, they have been ignored, or old ones used instead.
I can't figure out what's wrong.
Some more information about the set-up:
1. The computer can connect to the internet - actually, I'm doing this over ssh from a computer on the other side of the world.
2. An almost-identical computer with the same setup connected to the same ethernet switch as the above computer has a very different result:

Code:
Hit http://kr.archive.ubuntu.com karmic Release.gpg
Ign http://kr.archive.ubuntu.com karmic/main Translation-en_US                 
Ign http://kr.archive.ubuntu.com karmic/restricted Translation-en_US           
Ign http://kr.archive.ubuntu.com karmic/universe Translation-en_US             
Ign http://kr.archive.ubuntu.com karmic/multiverse Translation-en_US           
Hit http://kr.archive.ubuntu.com karmic-updates Release.gpg                    
Hit http://security.ubuntu.com karmic-security Release.gpg                     
Ign http://security.ubuntu.com karmic-security/main Translation-en_US          
Ign http://kr.archive.ubuntu.com karmic-updates/main Translation-en_US         
Ign http://kr.archive.ubuntu.com karmic-updates/restricted Translation-en_US
Ign http://kr.archive.ubuntu.com karmic-updates/universe Translation-en_US
Ign http://kr.archive.ubuntu.com karmic-updates/multiverse Translation-en_US
Hit http://kr.archive.ubuntu.com karmic Release
Hit http://kr.archive.ubuntu.com karmic-updates Release                        
Ign http://security.ubuntu.com karmic-security/restricted Translation-en_US    
Ign http://security.ubuntu.com karmic-security/universe Translation-en_US      
Ign http://security.ubuntu.com karmic-security/multiverse Translation-en_US    
Hit http://security.ubuntu.com karmic-security Release                         
Hit http://kr.archive.ubuntu.com karmic/main Packages                          
Hit http://kr.archive.ubuntu.com karmic/restricted Packages                    
Hit http://security.ubuntu.com karmic-security/main Packages                   
Hit http://kr.archive.ubuntu.com karmic/main Sources       
Hit http://security.ubuntu.com karmic-security/restricted Packages
Hit http://security.ubuntu.com karmic-security/main Sources
Hit http://security.ubuntu.com karmic-security/restricted Sources
Hit http://security.ubuntu.com karmic-security/universe Packages
Hit http://kr.archive.ubuntu.com karmic/restricted Sources
Hit http://kr.archive.ubuntu.com karmic/universe Packages                      
Hit http://security.ubuntu.com karmic-security/universe Sources                
Hit http://security.ubuntu.com karmic-security/multiverse Packages             
Hit http://security.ubuntu.com karmic-security/multiverse Sources              
Hit http://kr.archive.ubuntu.com karmic/universe Sources                       
Hit http://kr.archive.ubuntu.com karmic/multiverse Packages
Hit http://kr.archive.ubuntu.com karmic/multiverse Sources 
Hit http://kr.archive.ubuntu.com karmic-updates/main Packages
Hit http://kr.archive.ubuntu.com karmic-updates/restricted Packages
Hit http://kr.archive.ubuntu.com karmic-updates/main Sources
Hit http://kr.archive.ubuntu.com karmic-updates/restricted Sources
Hit http://kr.archive.ubuntu.com karmic-updates/universe Packages
Hit http://kr.archive.ubuntu.com karmic-updates/universe Sources
Hit http://kr.archive.ubuntu.com karmic-updates/multiverse Packages
Hit http://kr.archive.ubuntu.com karmic-updates/multiverse Sources
Reading package lists... Done
which makes me wonder if it's a software problem rather than a hardware one. I've looked around the internet for a solution but can't find the exact same problem I'm having. If anyone can help I'd appreciate it! Thanks in advance.