轉載：http://dsd007.blog.sohu.com/169335106.html
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如果某臺Linux服務器ping不通域名, 如下提示:
# ping www.baidu.com
ping: unknown host www.baidu.com
如果確定網絡沒問題的情況下, 可以通過如下步驟尋找解決辦法:
1) 確定設置了域名服務器, 沒有的話, 建議設置Google的公共DNS服務, 它應該不會出問題的
# cat /etc/resolv.conf
-------------------------------------------------------------------
nameserver 8.8.8.8
nameserver 8.8.4.4
-------------------------------------------------------------------
2) 確保網關已設置
# grep GATEWAY /etc/sysconfig/network-scripts/ifcfg*
-------------------------------------------------------------------
/etc/sysconfig/network-scripts/ifcfg-eth0:GATEWAY=192.168.40.1
-------------------------------------------------------------------
ps:ubuntu 10.3 找不到此文件，也許版本不對
3) 確保可用dns解析
# grep hosts /etc/nsswitch.conf
-------------------------------------------------------------------
hosts: files dns
-------------------------------------------------------------------
如果以上哪個有問題, 修正後, 再測試, 應該就沒問題了:
#ping -c 3 www.baidu.com
PING www.a.shifen.com (220.181.6.175) 56(84) bytes of data.
64 bytes from 220.181.6.175: icmp_seq=0 ttl=50 time=9.51 ms
64 bytes from 220.181.6.175: icmp_seq=1 ttl=50 time=8.45 ms
64 bytes from 220.181.6.175: icmp_seq=2 ttl=50 time=8.97 ms
--- www.a.shifen.com ping statistics ---
3 packets transmitted, 3 received, 0% packet loss, time 2002ms
rtt min/avg/max/mdev = 8.450/8.977/9.511/0.446 ms, pipe 2
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