Difference between host name and domain name

• hostname is the name given to the end-point (the machine in question)
  • and will be used to identify it over DNS if that is configured
• domain is the name given to the 'network'
  • it will be required to reach the network from an external point (like the Internet)

It is usually written in the form,

hostname.domain.com -- for example

If you are in (say) a college campus named called 'The-University',
and its domain is called 'theuniversity.org',
a machine on the campus network called 'mymachine' would be addressed as, 'mymachine.theuniversity.org'.

If you were trying to connect to this machine from your home network,
you would address it with that full name.
The domain part would reach you to the campus network
and the hostname would let you reach the exact machine in the campus.
^{I am avoiding the details of IP Addressing and gateways here.}

For this reason, while accessing the machine from another machine within the campus
may work with just the hostname (mymachine) without the use of the domain name.

To taken an analogy, if you are in the same city, the street name suffices.
But, to address a place in another city, you would usually add the city name after the street.

For a more detailed reading
the Wikipedia page on Domain Name Service could be a good starting place.

• When configuring DNS, the DNS Server Name would be required.
  This is a hostname (the server is an addressable machine).
• An IP address cannot point to a Domain Name,
  It can however point to a domain name server (DNS).

What is the difference between hostname and domain name?

A domain is something which you register and which points to your DNS servers^*0. These DNS servers^*1 can answer queries for hosts within that domain.

Note that these hosts do not have to be on the same network.

Example:
Gameforge^*2 is a firm with some 'Freemium' games. It has servers in multiple countries. It has one single domain called gameforce.com.

s13.gameforce.com may point to a server in the UK (and an a network in the UK), while
s14.gameforce.com may point ot a server in Germany.

Network location is not tied to the domain name.

A host is a computer on a network. That host can have one more more NICs and can have IP adresses.

Especially in regards to NIC

In the case of most home computers the desktop or laptop has one active NIC and one IP, but it is possible to have multiple IPs per NIC, or use multiple NICs. For more details on that look up multi-home.

I hope that this last part answers the 'in regards to NIC'. If not then please specify your question a bit more.

^*0 Or to the DNS servers of someone who manages your domain for you.
^*1 At least two DNS servers in different locations are recommended.
^*2 I am not affiliated with them. It is just the first example I thought of.