What is Network Protocol

In a communication network, when two entities exchange information between them, they must be agreed upon a common set of rules and guidelines. Such a set of rules and regulations which govern data communication between the devices is called network protocol.

Different protocols have their own set of rules and regulations in order to perform specific processes during the exchange of information between the devices. Such protocols are operated in different layers of network models. Some of the most commonly used protocols are listed below:

  • HTTP (HyperText Transfer Protocol)
  • HTTPS (HyperText Transfer Protocol Secure)
  • SMTP (Simple Mail Transfer Protocol)
  • POP (Post Office Protocol)
  • IMAP (Internet Message Access Protocol)
  • FTP (File Transfer Protocol)
  • Telnet
  • DNS  (Domain Name Service)
  • DHCP (Dynamic Host Configuration Protocol)
  • TCP (Transmission Control Protocol)
  • UDP (User Datagram Protocol)
  • IP (Internet Protocol)
  • ICMP (Internet Control Message  Protocol)
  • ARP (Address Resolution Protocol)
  • RARP (Reverse Address Resolution Protocol)

HTTP  ( HyperText Transfer Protocol) is an application layer protocol of the TCP/IP model and is designed to transfer hypertexts between the web browser and the webserver. HTTP helps to display webpage contents received from the remote webserver to the client’s web browser. A website contains a collection of web pages that are hyperlinked with each other. HTML tags are used for creating hyperlinked pages.

Whenever a client wants to access a website on the internet, he/she sends an HTTP request by just typing in the websites name in the address bar of the web browser. This request is received by the remote web server machine and responds to the client’s request accordingly.

HTTPS ( HyperText Transfer Protocol Secure) is a standard protocol to have secure communication between the client and the webserver. It is an extension of HTTP. HTTPS helps in data transfer between the client’s browser and the web server in an encrypted format. By doing this, no hacker and other external threat can intercept or modify the data. Hence, the data remain fully secured throughout the communication session between the client and the webserver.

SMTP ( Simple Mail Transfer Protocol) is also an application protocol and is designed for an email client for sending outgoing email. Whenever the client wants to send the mail, it initiates the TCP connection with the SMTP server which is always listening to the e-mail client. Once, the TCP connection is established, the client sends the mail to the SMTP server. Further, the SMTP server forwards the mail to the desired destination client.

POP (Post Office Protocol) is the most common protocol is used by an email client to receive incoming mail. It makes it possible for the client to download messages from the mail server to the client machine. POP came into existence in 1984 as POP1. After that POP2 was released and finally POP3 in 1988. Above all, POP3 is the most predominantly used standard to retrieve mail from a mail server in a client-server architecture. It works along with SMTP for an end to end e-mail communication. Generally, POP3 is used in such an environment where the client uses a single machine to retrieve the e-mail message from the mail server.

IMAP ( Internet Message Access Protocol) is also a popular e-mail receiving protocol and provides the best alternative for POP3. Generally, IMAP  has the ability to provide synchronization for those who log into their mailbox through multiple devices like computer, laptops, smartphones etc. IMAP further provides better security and encryption than POP3.

FTP (File Transfer Protocol) is the most commonly used application layer protocol of  TCP/IP stack and is used for transfer files over the internet. Transferring files from client to server is called uploading and from server to client is called downloading. FTP client software is used to gain access to FTP service.

Telnet is a standard protocol that is allowed to connect remote computer over the TCP/IP network. It is a command-line interactive program to communicate with remote devices such as routers, managed switches, computers, modems etc. using a virtual terminal connection.

DNS (Domain Name Service) is also a very important application layer protocol and designed to resolve the domain name into an IP address.

DHCP ( Dynamic Host Configuration Protocol) allows dynamic allocation of IP address to the host in a computer network.

TCP (Transmission Control Protocol) is a transport layer protocol in TCP/IP network. TCP is regarded as a connection-oriented protocol. The connection is established between the application programs and then the information is being exchanged between them. It is also said to be a reliable protocol because the sender waits for acknowledgement for every segment sent by the source to the destination.

UDP (User Datagram Protocol) is another very important transport layer protocol that is an alternative to TCP.  It is considered to be a connectionless and unreliable protocol. Unlike TCP, UDP doesn’t initiate and establish any session between the source and the destination.

IP (Internet Protocol) is a very important communication protocol in the TCP/IP protocol suite. The main function of IP is to deliver data packets from source to destination. It provides an addressing scheme called IP address for all the hosts. Each host connected with the network must have a unique IP address in order to get identified in the network.

ICMP ( Internet Control Message Protocol) is a network layer protocol which deals with error-reporting of network status. ICMP helps to identify the problems and connectivity of the destination host by sending ICMP packet.

ARP (Address Resolution Protocol) is a communication protocol that works between layer 2 and layer 3 of the OSI model and responsible for mapping dynamic Internet protocol version 4 address to permanent physical address ( mac address) in a local area network.

RARP (Reverse Address Resolution Protocol) is a protocol that is the opposite of ARP.  RARP is responsible for resolving MAC address to IP version 4 address.

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