• Connection: a link between two devices, carrying Packets of information.
  • Packet: Packets are the basic element of communication over a Connection. Each Packet containers a Header and Payload.
  • Header: Packets have a header portion that contains information about the packet including the source and destination, timestamps, network hops, etc.
  • Body/Payload: The main portion of a packet, containing the actual data being transfered.
  • Port: an address on a single machine that can be tied to a specific piece of software. It is not a physical interface or location, but allows your server to be able to communicate using more than one application.
  • NAT: NAT stands for network address translation. It is a way to translate requests that are incoming into a routing server to the relevant devices or servers that it knows about in the LAN. This is usually implemented in physical LANs as a way to route requests through one IP address to the necessary backend servers.
  • VPN: VPN stands for virtual private network. It is a means of connecting separate LANs through the internet, while maintaining privacy. This is used as a means of connecting remote systems as if they were on a local network, often for security reasons.
  • Network Range: each range is divisible into a range of network addresses, and host (device) addresses.
  • IPv4: is a 32-bit address, expressed as a set of 4 octets.
  • IPv6: is a 128-bit address, expressed as 8 sets of 4 hexadecimal numbers (7.9×10^28 times as many addresse options than IPv4)
  • The first part of an IPv4 address identifies the network, the rest identifies the host within the network.
  • Private network are reserved within:
    • class A's private network address space/range: (big networks)
    • Class B's private network address space/range: to (medium networks)
    • Class C's private network address space/range: to (small networks)
  • Subnetting: the process of dividing a network address space into smaller sections.
  • NetMask: a 1/0 notation of the amount of address bits used for the Net portion of the address.
    • For the range, the bit NetMask is notated in binary as 11111111-11111111-11111111-0000000, which in decimal is notated as:,
  • By default, each Network has only one Subnet. This default Subnet contains all the host addresses.
  • Subnet mask: another NetMask used to further divide the network.


Net Address192.168.1.x
Host Addressx.x.x.9
Full Address192.168.1.9In Decimal notation
Full Address11000000-10101000-00000001-00001001In Binary notation
NetMask11111111-11111111-11111111-00000000The Network BitMask
AND11000000-10101000-00000001-00000000Apply AND to both the address and Netmask and you get the Network portion
NAND00000000-00000000-00000000-00001001Apply NAND to both the address and Netmask and you get the Host portion