Information Technology » Definitions


Network Cards, IP Addresses, and Ports


Media Access Control (MAC) or Network Interface Card (NIC)These terms are synonymous with one another and some use MAC Address and some use NIC.  Either way, they both mean the same thing.  The MAC address is a 12 digit alpha-numeric “code” or address that identifies a specific piece of hardware in anything that connects to the Internet.   The first six digits identify the manufacturer and the last six digits represent the serial number.  The MAC/NIC address is typically represented in two digit sets, separated by either a dash (-) or a colon (:).  (;a=blob_plain;f=manuf)  


IP Address – An Internet Protocol (IP) address sort of like the physical address of your house (4781 Hereford Farm Road).  IP Addressing can become tricky since there are now two different versions of IP; version 4 (IPv4) and version 6 (IPv6).  For our description and just about anything you will come across, IPv4 is what you will need to know.  IP addresses are groups of numbers between 0 and 255.  Each group of numbers is known as an  “octet”…or eight bits of data (represented as ###.###.###.###)  The first one or two octets typically represent who the issuer of the IP address is.  For instance, the IP Address starting with has been assigned to Knology Inc.  (


Numbers that start with 10.x.x.x or 196.168.x.x, or 127.x.x.x are considered “private addresses” and can’t traverse the internet, only internal to your local network.  We’ll get into more of how this works in our Network Address Translation (NAT) and Port Address Translation (PAT) later in the definitions.  Keep in mind that just about every number between 2 and 254 (0, 1, and 255…along with the other private addresses will never be assigned by a Internet Service Provider)


PORTS – A port is a number that represents a service running on a computer.  Port numbers between 0 and 1024 are reserved for specific services, while 1025 through 65535 are used for a plethora of application services.  For instance, when you type, the computer knows to that you are going to web and uses port 80 to get there.  http is port 80. 


To better understand, pretend you are standing in front of the empire state building.  The physical street address is the IP address, and each window represents a port, or way to get into the building for a specific purpose.  Here are some more well known ports/windows you may use but just don’t realize it:


                Port 443               This is Secure Socket Layer (SSL)/HTTPS

                Port 21                  File Transfer Protocol (FTP)

                Port 23                  Telnet

                Port 53                  Domain Name Services (DNS)….and a good Segway….



Nodes – Nodes are simply a device that gets an IP address.  Computers, printers, wifi antennas, cell phones, etc all are “nodes” on a network.



DHCP, DNS, and Default Gateways


Dynamic Host Configuration Protocol (DHCP) – When you first start a computer that contains MAC, your computer does a “shout out” to whatever network it is on stating “HEY…HERE I AM….I NEED AN IP ADDRESS… HELLO  HELLO????  Each network has servers located on them called DHCP Servers.  These servers issue a publically routable IP Address to your computer so it can talk.  Without an IP Address, your computer would not exist on the Internet.  Here is how it occurs:

  1.        Client computer broadcasts “I need an IP address”
  2.        DHCP server receives the request and sends back an acknowledgement asking if you want a specific IP address.
  3.        Client accepts the IP address and sends back computer name and some other information which gets logged into the DHCP server with the information shown below.


Domain Name Services (DNS) – Humans remember names better than numbers.  Could you imagine if you had to remember instead of  Well, this is what a DNS server does for you (amongst other things).  DNS Servers convert numbers to names and names to numbers.  There are literally thousands of DNS servers across the internet telling computers what the numeric value is for a name so your computer can get to the correct website.  Without DNS servers, you would have to know the numeric value in order to connect to the correct website.


Default Gateways (Routers) – Let’s get a little trickier now.  Remember, the first/second/third set of numbers in an IP address represent the “network” and what is left is considered a node.  For almost all home versions of wifi routers, each manufacturer will have a default Internal Private Network predefined for you.  Here are some of the more popular ones and what the default internal networks are:


Linksys:           192.168.1.x (192.168.1. is the network.  The last octet is will be assigned to whatever is trying to get          an IP address.)


Netgear:          192.168.0.x


Belden:            192.168.2.x


Typically, the Default Gateway/Router IP address will be the number 1.  In our example, Linksys Default Gateway will be   this tells the end computer where to go if the computer doesn’t know where to send traffic.  It’s sort of like a traffic director.