WHM – Networking Setup

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In the Networking section of WHM you will find by default 3 gadgets:

1. Hostname
2. Nameserver IPs
3. Resolver configuration

Each of these gadgets is extremely important both for you and for the server. Especially if you want the server to be publicly available.

Let’s see the first gadget, Hostname:

The hostname always has to be unique, this is the name of your server. Usually this name, nickname if you like is chosen from the Greek mythology, for example Zeus, and this name is snapped to a fully qualified domain name owned by you, like example.com. This domain name will have to use the server’s nameservers, this will be the first domain you will add to the server. Usually you have to specify this domain name when you order the server. So, a hostname will look like something like this:
zeus.example.com
But it can be very well hera.example com or sinatra.example.com, it doesn’t really matter. The only thing which matters is that this hostname will have to be unique on the server, you will not be able to use it for traditional website access or any other thing, it’s the server’s name.
This hostname can also be used to access cPanel and WHM, so in conformance with the applicable RFC (1035 if am not mistaken) this hostname should never begin with a number, nor end with a hyphen (-).

Nameserver IPs:

This is very important gadget as well, if you want your server to be publicly accessible. What are nameservers? Nameservers tells a client on which IP a website can be found. They are part of the DNS. Internet works based on IPs (like 127.0.0.1), but remembering IPs is hard. For example is more likely you remember www.Google.com than 72.14.205.100, which is one of Google’s IPs. So, the big guys invented domain names like google.com. This is what you type in the address bar of the browser to arrive on Google’s website and perform a search to find out what kind of underwear did Britney wear yesterday.
But the internet still works based on IPs, and nameservers are who basically translates the domain names in IPs. OK, I’ll try to explain this. Imagine a conversation between your PC and the nameserver, like this one:

You: Hey, gTLD nameserver. Do you know where can I find google.com?
NS: Hello, sure. It’s located on the 72.14.205.100 IP. Go there.
You: Thanks!

Don’t imagine for a second that it’s this simple, it’s way more complicated as there are at least 2 other men-in-the-middle before you get that info.
So, the nameservers your server will manage will also have to have — if possible — a unique IP. You will see, depending on how many IPs you got with the server, at least 1 IP. It’s the nameserver of the private network. If there are more than one, each is an existent namesrver. To delete a nameserver, just click the small cross on its right.
To create a new nameserver, put its name in the box below the table containing the IP(s). It will create the nameserver and will assign the next available IP to the name. The name you choose also has to be in conformance with the applicable RFC.
After you created the nameserver on your server, you will have to go to your registrar and register the nameserver. Since your server is not authoritative, you can’t do this without a registrar.

Resolvers’ configuration:

This is a wizard through which you can manage your /etc/resolv.conf . The IPs you will put here are also very important as they are used for dns resolution. When you leased the server, the datacenter most likely provided you at least one nameserver IP you can use. The problem is that you should use two. The first is the primary, the second is for backup. If these nameservers are down, your server is likely will have difficulties querying the MySQL databases, so if the DC didn’t provide you nameserver IPs you can use, choose carefully. But your best option is to contact the datacenter and pick their brains until they give you at least one IP of a DNS.
Also, while the server may function properly without any nameserver IP in the resolv.conf, the connections made to the server will be extremely slow.