今天,我在玩vmware的時候,用ping命令ping www.baidu.com的時候,結果顯示unkown hosts www.baidu.com,但ping某一ip是正常的.
實例如下:
[root@yangguoqiang ~]# ping www.baidu.com
ping: unknown host www.baidu.com
[root@yangguoqiang ~]# ping 119.29.25.60
PING 119.29.25.60 (119.29.25.60) 56(84) bytes of data.
64 bytes from 119.29.25.60: icmp_seq=1 ttl=128 time=41.9 ms
64 bytes from 119.29.25.60: icmp_seq=2 ttl=128 time=43.3 ms
64 bytes from 119.29.25.60: icmp_seq=3 ttl=128 time=41.7 ms
64 bytes from 119.29.25.60: icmp_seq=4 ttl=128 time=41.7 ms
64 bytes from 119.29.25.60: icmp_seq=5 ttl=128 time=42.5 ms
經檢查得出,DNS沒有配置好:
查看/etc/resolv.conf發現:
nameserver xxx.xxx.xxx.xxx
於是重新配置/etc/resolv.conf
nameserver 8.8.8.8 (google域名主服務器)
nameserver 4.4.4.4 (google域名備用服務器)
配置完成後保存退出.
檢測結果:
# ping www.baidu.com
PING www.a.shifen.com (61.135.169.125) 56(84) bytes of data.
64 bytes from 61.135.169.125: icmp_seq=1 ttl=128 time=20.8 ms
64 bytes from 61.135.169.125: icmp_seq=2 ttl=128 time=21.0 ms
64 bytes from 61.135.169.125: icmp_seq=3 ttl=128 time=20.8 ms
使用dig命令:
# dig www.baidu,com
; <<>> DiG 9.8.2rc1-RedHat-9.8.2-0.17.rc1.el6_4.6 <<>> www.baidu,com
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 9710
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 1, ADDITIONAL: 0
;; QUESTION SECTION:
;www.baidu,com. IN A
;; ANSWER SECTION:
www.baidu,com. 5 IN A 220.250.64.26
顯示正常.
但是服務器重啓之後,又會出現域名無法解析的情況,經過分析發現:
/etc/sysconfig/network-scripts/ifcfg-eth0文件中
PEERDNS=no ###DNS系統關閉狀態
因此每次重啓後DNS系統都無法解析域名。
可以將此項註釋或者改爲yes,修改完成以後,重啓網絡即可。