Solution to ping: unknown host error under Linux

Sometimes ping command errors occur on Linux servers. Let’s summarize them today

If a Linux server cannot ping the domain name, the following prompts:

[root@localhost ~]# ping www.pythontab.com

ping: unknown host www.pythontab.com

First make sure the router is connected and the router can access the external network. You can confirm by accessing the gateway

[root@localhost ~]# ping 192.168.1.1

PING 192.168. 1.1 (192.168.1.1) 56(84) bytes of data.

64 bytes from 192.168.1.1: icmp_seq=1 ttl=64 time=2.96 ms

64 bytes from 192.168.1.1: icmp_seq=2 ttl=64 time= 1.75 ms

If you are sure that there is no problem with the network, you can find a solution through the following steps:

1) Make sure the domain name server is set up. If not, it is recommended to set up Google’s public DNS service. It should not go out. The problem is

[root@localhost ~]# cat /etc/resolv.conf

search localdomain

Because my DNS is not set up, pinging from the external network is blocked. Add dns to the file

[root@localhost ~]# vi /etc/resolv.conf

search localdomain

nameserver 202.98.96.68

nameserver 61.139.2.69

~

2) Make sure the gateway is set

# grep GATEWAY /etc/sysconfig/network-scripts/ifcfg*

--------------------- ---------------------------------------------

/etc/ sysconfig/network-scripts/ifcfg-eth0:GATEWAY=192.168.40.1

--------------------------------- ----------------------------------

If it is not set, add the gateway as follows:

# route add default gw 192.168.40.1

Or manually write the /etc/sysconfig/network-scripts/ifcfg* file, restart the network service:

# service network restart

3) Make sure dns resolution is available

# grep hosts /etc/nsswitch.conf

---------------------------------- ------------------------------------

hosts: files dns

------ -------------------------------------------------- -----------

If there is a problem with any of the above, correct it and test again, it should be fine: