amazon ec2 instance under vpc cannot resolve own hostname

Question

i noticed when i tried to restart apache i get the following warning: httpd: apr_sockaddr_info_get() failed for ip-10-0-0-55 httpd: Could not reliably determine the server's fully qualified domain name, using 127.0.0.1 for ServerName

and also when i run hostname -i, i get "hostname: Unknown host"

so i think it's a network config issue, most likely about dns. it's besides those symptoms the server runs good without any other issues. but this warning message just bugs me... maybe there's something wrong with my vpc configuration. but for the most part, i just follow the steps in this guide, http://docs.aws.amazon.com/AmazonVPC/latest/GettingStartedGuide/ExercisePreqs.html

thx for any helpful pointers!

Answer 1

You need to specify a ServerName directive in the Apache configuration like this:

ServerName yourdomain.com

or

ServerName localhost

Apache is not finding a ServerName so it is trying to make an educated guess at it. It has tried to figure it out from your hostname (the first message) and, not finding anything else it is assuming:

ServerName 127.0.0.1

i.e localhost (as per the second message).

This setting is not so important (apart from the error message) unless you have multiple Name Based Virtual hosts where it becomes crucial as it is the only way Apache can distinguish which host the client is trying to access.