Linux can ping ip cannot ping domain name detailed

Today, in the development of colleagues, the intranet can not access their own servers through the domain name! And then did the following tests to discover the problem:

[Root@itmop ~]# Ping www.downcc.com

Ping:unknown Host Www.downcc.com

[Root@itmop ~] #ping 192.168.1.1

PING 192.168.1.1 (192.168.1.1) bytes of data.

Bytes from 192.168.1.1:icmp_seq=1 ttl=64 time=0.537 ms

Bytes from 192.168.1.1:icmp_seq=2 ttl=64 time=0.430 ms

-192.168.1.1 Ping statistics-

2 packets transmitted, 2 received, 0% packet loss, time 999ms

RTT Min/avg/max/mdev = 0.430/0.483/0.537/0.057 ms

[Root@itmop ~] #cat/etc/host.conf

Order Bind,hosts

After a search after the solution, the reasons and methods are as follows:

[Root@itmop ~]# grep host/etc/nsswitch.conf

#hosts: DB Files Nisplus NIS DNS

Hosts:files

Host only find files do not go to DNS, it should be hosts:files DNS!