IP address and Gateway, DNS, subnet

IP(Internet + Protocol) Address

• Internet means inter + network as the name suggests
• Several small networks are connected to form a large network
• When computers are physically connected using an ethernet cable, it becomes a small network.
• This is called LAN (Local Area Network)
• LAN + LAN ==> Internet
• Protocols on control, connection or communication and data transfer between computers on the Internet
• an address of a computer

Gateway

• LAN connects to the external network through a computer acting as an entrance –> that computer is a gateway
• Gateway: A network point that serves as an entrance to another network.

DNS

• DNS emerged in order for devices to recognize each other in computer networks and because it is impossible to memorize IP addresses one by one
• DNS: Converts human-readable domain names into numeric identification numbers to find the address of a specific computer

  subnet

• Abbreviation for subnetwork
  • A network that belongs to an organization but can be recognized as a separate network
• If you look at the subnet, it is composed of 255 and 0.

• By designating the network part as 255 and the host part as 0, you can know where the IP address is from the network address and from where the host address is.

  • For example, if subnet is 255.255.0.0 and IP address is 1.2.3.4, up to 1.2 are network addresses and 3.4 are host addresses. Again, for example, if the subnet is 255.255.255.0 and the IP address is 1.2.3.4, then 1.2.3 is the network address and the last 4 is the host address.

  • So, what exactly do the network part and the host part define?
    • The network part means the area where data can be transmitted without going through a router when data is transmitted for communication.
    • The host part refers to each PC.
  • It will be easier to understand if you look at an example. Let’s say you have 3 hosts.

  • Assume that the IP of host a is 210.170.1.1, the IP of host b is 210.170.1.2, and the IP of host c is 210.170.2.1.

  • If the subnet mask of these hosts is 255.255.255.0, the network address part is up to the third part. Therefore, up to 210.170.1., the same a and b can be directly connected to the same network.

  • If the subnet mask is 255.255.0.0, a, b, and c all become the same network and direct connection is possible.