[Warning] IP address ‘X.X.X.X’ could not be resolved: Name or service not known

In one of  RDS instance getting  warning messages in the error log file.

“[Warning] IP address ‘X.X.X.X’ could not be resolved: Name or service not known”

I have checked and DNS lookup is working fine.

In RDS hope you all aware about the concept of Security Groups where we white list the IP address so that they can connect the RDS instance.

Now coming back to problem statement. When ever you trying to make a connection with instance, MySQL has to do a reverse lookup on IP address connecting to it.

For Example: ‘deepakdba@’ is the user name which is created to make DB connection. Now when you initiate the request to make the DB connection than it will do the reverse lookup to check whether the IP is from the correct domain or not.

To resolve this warning you have two options.

  1. Create a rule in the security group to whitelist the ( range by doing this you are exposing the database instance to the internet user. I will not recommend it.
  2. You can switch this off with putting “Skip_name_resolve” parameter in your my.cnf file.


Hope this will help you.


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