What's the difference between `server.com` and `server.com.` in the search section of an `/etc/resolv.conf` file? 

```
user@host /etc/sysconfig/network-scripts $ head -n 3 /etc/resolv.conf
# Generated by NetworkManager
domain sub.company.com
search sub.company.com sub.company.com. company.com. company.com

```