How To Configure ISA Proxy/Auth Setting For Yum
I was running CentOS in my LAN for my personal use and there are MS ISA servers for proxying and each user has to use his/her user name & password for Internet. So when I used my credentials in my web browser I had no problem but when I was going to do yum no success. After some googling I found this solution.
Get more at HowtoForge