# nslookup yahoo.co.jp Server: 192.168.26.2 Address: 192.168.26.2#53 Non-authoritative answer: Name: yahoo.co.jp Address: 124.83.187.140 Name: yahoo.co.jp Address: 203.216.243.240
# curl yahoo.co.jp The document has moved <A HREF="http://www.yahoo.co.jp/">here</A>.<P> <!-- p11.f11.top.tnz.yahoo.co.jp uncompressed/chunked Fri Feb 8 10:40:54 JST 2013 -->
etc…
⇒ 失敗したら、DNS(nameserver) の設定を疑う
# vi /etc/resolv.conf
; generated by /sbin/dhclient-script nameserver 192.168.80.1 search localdomain
# yum clean all # yum update
それでもダメなら
# rm -rf /var/cache/yum # yum check-update # yum update