If I setup my hosts files such that they reference all other ec2 nodes using the internal ip addresses, will this work or do I have to use the external ip addresses?

Do I need to specify anything in my security group to get internal ip addresses to work?

e.g. /etc/hosts

ip-10-11-12-13.internal  some_node_name

If I do this, can I reference some_node_name anywhere in my scripts where I would have used the ip address previously?

On my puppet agent servers, I have a reference to my puppet master like:

public-ip-here puppet

When I reboot my puppet agent's, syslog shows they couldn't find the master with the message: getaddinfo : name or service not known

I did get it to work by updating /etc/default/puppet

and I added to the options:

--server=public-ip-here

From what I read, puppet will by default try using 'puppet', and I set this in my hosts file so why wouldn't it be picking this up?