Linux could not ping the gateway and could not ping the other IP address reason lookup __linux

background

Server reboot once, every time there will be a little problem, this time the problem is not normal access to the extranet (because the server needs to pass the Campus network certification), so began to toss.

Process
First look at whether the DNS or something is normal,

And then visit baidu.com and try it.

Found not normal access to baidu.com, so judge whether the campus network certification has not been, visit the Campus Network Certification site (172.18.2.2), found that can not ping pass.
Then began to think (PS: Host ip:172.18.72.18),

View routing Information

The default route is 172.18.72.254

Access the gateway again Ping 172.18.72.254 can ping

However, could not ping 172.18.2.2

Quite puzzling ...

It is reasonable to say that this is not in the same network segment appeared in the network unreachable situation, but test another 192.xxx host Access 172.18.2.2 incredibly can. There is a problem with the description or configuration.

First, empty the current routing information (see network card information, and then empty):

After emptying, reboot the network card:

Then go and check the configuration file for the NIC (my eth0)

Execute command Service after configuration network Restart should be no problem, then ARP check (normal work)

Execute command dhclient again visit 172.18.2.2, pass.

Summary
Keep a record so you don't have to worry about any of that.