Please paste your terminal session here; it would help a lot to see which commands you're running, and where the error happens.
Can you connect to the internet without problems? Look in your /etc/apt/sources.list; there should be one or more hostnames (http://ftp.this-is-what-I-am-talking....com/not-this/
or-this). Try running the command "host ftp.this-is-what-I-am-talking-about.com" (replace the name with your actual name). What is the result? What is the name?
If the hostname is ftp.ubuntu.com, then host should spit out three lines, containing "ftp.ubuntu.com A ip-address", where ip-address is one of 126.96.36.199, 188.8.131.52, 184.108.40.206. Is this what you see?
How are you trying to get updates? "sudo apt-get update" or "sudo aptitude update" or something else?
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