MySQL exception: Unauthenticated user attempts to log in

Today's corporate database has stalled and blocked problems, check the database when found, show processlist; you can see a lot of:

....

:　3436942　:　unauthenticated　user　:　192.168.0.4:49607　:　:　Connect　:　:　login　:

:　3436943　:　unauthenticated　user　:　192.168.0.4:49608　:　:　Connect　:　:　login　:

.....

Constantly have unauthenticated users try to login but did not pass, have a classmate Google out, found that the domain name resolution is related to:

No matter what the client connection, the server side will be DNS back to the client to obtain the client domain name or host name.

It is likely that the DNS server is out of order to cause unresolved-although the parse result should be no

Classmate by adding Skip-name-resolve in my.cnf

To prevent reverse domain name resolution (or add parameter--skip-name-resolve to the startup command line).

This approach is also one of the recommended MySQL optimization methods.

But the disadvantage of this approach is that the host in the permission can no longer use the hostname, but to use the IP address, fortunately we configured the "%", so I prefer to use another way, is to add the corresponding host record in the/etc/hosts file.