在ubuntu(1204)更新时，出现错误E: Some index files failed to download.They have been ignored, or old ones used instead.
我使用的是官方源，昨天还好好的，今天安装软件包的时出现问题，打算更新源，出现了下列问题：
Ign http://archive.ubuntu.com precise InRelease
Err http://archive.ubuntu.com precise Release.gpg
Something wicked happened resolving 'archive.ubuntu.com:http' (-5 - No address associated with hostname)
Ign http://archive.ubuntu.com precise Release
Ign http://archive.ubuntu.com precise/main TranslationIndex
Ign http://archive.ubuntu.com precise/restricted TranslationIndex
Err http://archive.ubuntu.com precise/main amd64 Packages
Something wicked happened resolving 'archive.ubuntu.com:http' (-5 - No address associated with hostname)
Err http://archive.ubuntu.com precise/restricted amd64 Packages
Something wicked happened resolving 'archive.ubuntu.com:http' (-5 - No address associated with hostname)
Err http://archive.ubuntu.com precise/main i386 Packages
Something wicked happened resolving 'archive.ubuntu.com:http' (-5 - No address associated with hostname)
Err http://archive.ubuntu.com precise/restricted i386 Packages
Something wicked happened resolving 'archive.ubuntu.com:http' (-5 - No address associated with hostname)
Err http://archive.ubuntu.com precise/main Translation-en_US
Something wicked happened resolving 'archive.ubuntu.com:http' (-5 - No address associated with hostname)
Err http://archive.ubuntu.com precise/main Translation-en
Something wicked happened resolving 'archive.ubuntu.com:http' (-5 - No address associated with hostname)
Err http://archive.ubuntu.com precise/restricted Translation-en_US
Something wicked happened resolving 'archive.ubuntu.com:http' (-5 - No address associated with hostname)
Err http://archive.ubuntu.com precise/restricted Translation-en
Something wicked happened resolving 'archive.ubuntu.com:http' (-5 - No address associated with hostname)
W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/precise/Release.gpg Something wicked happened resolving 'archive.ubuntu.com:http' (-5 - No address associated with hostname)
W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/precise/main/binary-amd64/Packages Something wicked happened resolving 'archive.ubuntu.com:http' (-5 - No address associated with hostname)
W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/precise/restricted/binary-amd64/Packages Something wicked happened resolving 'archive.ubuntu.com:http' (-5 - No address associated with hostname)
W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/precise/main/binary-i386/Packages Something wicked happened resolving 'archive.ubuntu.com:http' (-5 - No address associated with hostname)
W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/precise/restricted/binary-i386/Packages Something wicked happened resolving 'archive.ubuntu.com:http' (-5 - No address associated with hostname)
W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/precise/main/i18n/Translation-en_US Something wicked happened resolving 'archive.ubuntu.com:http' (-5 - No address associated with hostname)
W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/precise/main/i18n/Translation-en Something wicked happened resolving 'archive.ubuntu.com:http' (-5 - No address associated with hostname)
W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/precise/restricted/i18n/Translation-en_US Something wicked happened resolving 'archive.ubuntu.com:http' (-5 - No address associated with hostname)
W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/precise/restricted/i18n/Translation-en Something wicked happened resolving 'archive.ubuntu.com:http' (-5 - No address associated with hostname)
E: Some index files failed to download. They have been ignored, or old ones used instead.
求帮忙～～