Agents trust the master only if they contact it at one of the valid hostnames specified when the master was installed.
On the node, if the results of puppet agent --configprint server don't return one of the valid DNS names you chose during installation of the master, the node and master can't establish communication.
- To edit the master's hostname on nodes, in /etc/puppetlabs/puppet/puppet.conf, change the server setting to a valid DNS name.
- To reset the master's valid DNS names, run:
puppet cert clean <MASTER_CERTNAME>
puppet cert generate <MASTER_CERTNAME> --dns_alt_names=<COMMA-SEPARATED_LIST_OF_DNS_NAMES>