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What is Internet Protocol (IP)?

Last Updated : 05 Aug, 2025
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The Internet Protocol (IP) is a set of rules that allows computers and other devices to communicate over the Internet. It ensures that information sent from one device reaches the correct destination by using a unique set of numbers known as IP addresses.

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Whether you're browsing websites, sending emails, or watching videos, the Internet Protocol helps manage how information travels, making sure everything works smoothly and efficiently.

Why is Internet Protocol Important?

The Internet Protocol is a fundamental component of the Internet and computer networks, responsible for delivering packets of data from the source host to the destination host based on their IP addresses. It ensures that packets of data get to the right destination from the source device.

Each device connected to a network is assigned an IP address, which serves as a "home address" for the device, enabling other devices to locate and send messages to it and providing the addressing and routing mechanisms the devices require for their communications.

IP works in conjunction with the Internet Control Message Protocol (ICMP) to send error messages and operational information (e.g., destination unreachable, echo requests), which inform senders about issues in packet delivery. Unlike some protocols, IP does not establish a connection before transmitting data, making it a connectionless protocol that allows for more flexible and efficient data transmission

These terms form the foundation for understanding how devices communicate and exchange data efficiently across a network.

primary_terminologies
  • IP Address: IP address is referred as a number sticker given to each device that belongs to the network which utilizes Internet Protocol to communicate. It serves two main purposes: host or network interface recognition, identifier or location addressing.
  • Packet: A packet is a parcel of data that is switched between an origin and a destination via the Internet or some other network that is based on the packet switching mechanism. This component mainly has a header and a payload.
  • Router: A router is a network device that (serves as) a forwarding point for data packets between computer networks. Routers carry out the traffic routing functions through the Internet.
  • IPv4: Internet Protocol version 4 (IPv4) is a protocol that tends to provide connectivity between the desktop computers online and that application layer is the wider application one that covers most of the Internet communications nowadays
  • IPv6: Internet Protocol version 6 (IPv6), the final iteration in the series of the upgrades to the Internet Protocol, is used for the purpose of identifying, locating and routing of various computers so that traffic through Internet can be transferred properly.

TOP 20 Essential Protocols

These protocols and ports are fundamental for network communication, troubleshooting, and securing services.

PortProtocolCommon ServiceUse Case
20TCPFTP (Data)File transfers (active mode)
21TCPFTP (Control)File transfer control
22TCPSSHSecure remote login, SFTP
23TCPTelnetRemote login (insecure)
25TCPSMTPSending email
53TCP/UDPDNSDomain name resolution
67UDPDHCP (Server)Assigning IP addresses
68UDPDHCP (Client)Receiving IP addresses
80TCPHTTPWeb traffic
110TCPPOP3Receiving email
123UDPNTPTime synchronization
135TCPMicrosoft RPCDCOM services on Windows
137UDPNetBIOS Name ServiceWindows file sharing
138UDPNetBIOS DatagramWindows file sharing
139TCPNetBIOS SessionWindows SMB traffic
143TCPIMAPEmail retrieval
161UDPSNMPNetwork management
443TCPHTTPSSecure web traffic
445TCPMicrosoft-DS (SMB)File and printer sharing
3389TCPRDPRemote Desktop Protocol

How Does IP Addressing Work?

Every device connected to a network (such as the internet or a local network) needs a unique identifier so it can be located and communicated with other devices. So, the IP address serves this purpose. IP addresses are used by routers to determine how to forward data packets across the internet or a local network. This is essential for the delivery of data between devices located in different geographical regions or network segments.

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IP addressing uniquely identifies each device on a network using IPv4 or IPv6 addresses, assigned either statically or dynamically through DHCP. DNS translates human-readable domain names into these IP addresses, while protocols like ARP (for IPv4) or NDP (for IPv6) map IPs to physical MAC addresses locally. Data is encapsulated into IP packets containing source and destination addresses, which are routed through network devices using routing tables and protocols such as OSPF or BGP to reach their target. In private networks, NAT allows multiple devices to share a single public IP, conserving address space and enhancing security by hiding internal addresses. Upon reaching the destination, packets are decapsulated and processed by the appropriate applications. This comprehensive system ensures accurate, secure, and reliable data delivery across interconnected networks.

What is an IP Packet?

An IP packets is the basic unit of data transmission in an IP network. It consists of a header and a payload:

  • Header: The header contains essential control information, such as the source and destination IP addresses, that helps routers determine where to send the packet.
  • Payload: The payload contains the actual data being transmitted. Once the packet reaches its destination, the data in the payload is delivered to the appropriate application or protocol

TRouters examine the IP header and use the destination IP address to determine the best route for the packet. The packet may pass through multiple routers before reaching its destination. Upon arrival, the packet is decapsulated, and the payload is passed to the relevant application on the receiving device.

IP Packet
IP Packet

How Does the IP Routing Work?

IP routing is a procedure of routing the information from the source to the recipient to enable its direction to the final destination. As we also know that the data is broken into several pieces, and then each piece will almost definitely go through several routers until these data ends up in the final destination. The path that the set of data package follows is determined by the routing algorithm.

Besides the size of packet and the header length, the design of the routing algorithm takes into account other factors related to determining the most suitable route for the data from the sender to the destination. At the arrival of the datagram at some router, then source address and destination address fields are employed with a routing table to decide the subsequent hop's address.

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IP Routing

Considering that it runs until it ultimately arrives at its desired point. The data which is getting distributed into multiple packages will be reached destination by travelling through different independent packets.

Example:

The TCP layer in an email server carries out this service by means of dividing the data into packets, providing numbers to each of the packets as well as to send these packets to the IP layer. This IP layer later resends the packet to the email server becoming the destination. On the recipient server, other way around, the TCP layer separates the data packets from the IP layer and remains its original text. This command goes to the mail application.


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