I'm relatively new to Linux and Ubuntu, so please bear with me. I'm setting up a Ubuntu 18.04 LTS VM that will act as a mail relay via postfix. I have that installed, and have configured those settings to match the old existing relay server that was set up years ago, at least as much as I can determine. My issues is, the connection from this new relay server is timing out, which I can see in the /var/log/mail.log file. This server is set up to obtain an IP via DHCP because of the way our network is set up. I work for a group that is affiliated with a university, but we're not directly part of the IT staff, so my group has their own IT department, of which I'm a part. In order to get anything on the University's network, we have to register the MAC address of the device, then once that registration is complete with the uni, they assign an IP address and the device gets a lease.
What I can't figure out is two-fold: first, how to look up what my lease information is. Second, in conjunction with that, how I can see what DNS servers are included with that lease. I've used a number of commands to try and look that information up, or glean it from Ubuntu in some way, but to no avail. I also have the Ubuntu desktop installed, as that was something the previous mail relay server had, just so I could be as 1:1 with my setup as possible, and I can't find any info via the Network section of the system settings either. I looked through http://manpages.ubuntu.com/manpages/bionic/en/man1/ for anything with 'dhcp' or 'dns' in the list, but couldn't seem to find a command I could throw at it to determine the answer to my question.
The other curious thing is, my network interface is labeled 'ens160' instead of 'eth0', which I thought was odd. In any event, I'm trying to determine what my DHCP and DNS info is, because I can ping some hostnames inside and outside the network, but I might be missing some internal DNS server entries, in which case, I'll need to know how to add those, but I also want to make sure I can clearly see what my setup is. Unfortunately,
ifconfig doesn't return much more than the IP, MAC, and interface name info. Anyway, sorry for the novella, but I'm just trying to figure out how to see the full networking details on my new server, so I can better troubleshoot the issue at hand.