1 "ping: unknown host www.baidu.com" 2 解决方案： 3 如果某台Linux服务器ping不通域名, 如下提示: 4 [root@localhost ~]# ping www.baidu.com 5 ping: unknown host www.baidu.com 6 7 首先确定已经连接上路由器，并且路由器能够访问外网，可以通过访问网关进行确定 8 9 [root@localhost ~]# ping 192.168.1.1 10 PING 192.168.1.1 (192.168.1.1) 56(84) bytes of data. 11 64 bytes from 192.168.1.1: icmp_seq=1 ttl=64 time=2.96 ms 12 64 bytes from 192.168.1.1: icmp_seq=2 ttl=64 time=1.75 ms 13 14 如果确定网络没问题的情况下, 可以通过如下步骤寻找解决办法: 15 1) 确定设置了域名服务器, 没有的话, 建议设置Google的公共DNS服务[nameserver 8.8.8.8], 它应该不会出问题的 16 17 [root@localhost ~]# cat /etc/resolv.conf 18 search localdomain 19 20 因为我的DNS没有设置所以导致了ping外网ping不通。将dns添加到该文件中 21 22 [root@localhost ~]# vi /etc/resolv.conf 23 24 search localdomain 25 nameserver 202.98.96.68 26 nameserver 61.139.2.69 27 ~ 28 2) 确保网关已设置 29 30 # grep GATEWAY /etc/sysconfig/network-scripts/ifcfg* 31 ------------------------------------------------------------------- 32 /etc/sysconfig/network-scripts/ifcfg-eth0:GATEWAY=192.168.40.1 33 ------------------------------------------------------------------- 34 35 如果未设置, 则通过如下方式增加网关: 36 37 # route add default gw 192.168.40.1 38 39 或者手工编写/etc/sysconfig/network-scripts/ifcfg*文件后, 重启network服务: 40 41 # service network restart 42 43 3) 确保可用dns解析 44 45 # grep hosts /etc/nsswitch.conf 46 ------------------------------------------------------------------- 47 hosts: files dns 48 ------------------------------------------------------------------- 49 50 如果以上哪个有问题, 修正后, 再测试, 应该就没问题了: 51 52 #ping -c 3 www.baidu.com 53 PING www.a.shifen.com (220.181.6.175) 56(84) bytes of data. 54 64 bytes from 220.181.6.175: icmp_seq=0 ttl=50 time=9.51 ms 55 64 bytes from 220.181.6.175: icmp_seq=1 ttl=50 time=8.45 ms 56 64 bytes from 220.181.6.175: icmp_seq=2 ttl=50 time=8.97 ms 57 --- www.a.shifen.com ping statistics --- 58 3 packets transmitted, 3 received, 0% packet loss, time 2002ms 59 rtt min/avg/max/mdev = 8.450/8.977/9.511/0.446 ms, pipe 2
转载自：http://www.cnblogs.com/happyhotty/articles/2539951.html