What is Network Protocol

In communication network, when two entities exchange information between them, they must be agreed upon common set of rules and guidelines. Such 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 (Hyper Text Transfer Protocol)
  • HTTPS (Hyper Text 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  ( Hyper Text Transfer Protocol) is an application layer protocol of TCP/IP model and is designed to transfer hyper texts between the web browser and the web server. HTTP helps to display webpage contents received from the remote web server to the client’s web browser. A website contains a collection of web pages which are hyperlinked with each other. HTML tags are used for creating hyper linked pages.

Whenever a client wants to access a website in internet, he/she sends HTTP request by just typing in websites name in 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 ( Hyper Text Transfer Protocol Secure) is a standard protocol to have a secure communication between the client and the web server. 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 web server.

SMTP ( Simple Mail Transfer Protocol) is also an application protocol and is designed for email client for  sending outgoing email. Whenever, 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, SMTP server forwards the mail to the desired destination client.

POP (Post Office Protocol) is the most common protocol  is used by email client to receive incoming mail. It makes possible for the client to download messages from the mail server to the client machine. POP came into existence during 1984 as POP1.After that POP2 was released and finally POP3 on 1988. Above all, POP3 is the most predominantly used standard to retrieve mail from mail server in client-server architecture. It works along with SMTP for end to end  e-mail communication. Generally, POP3 is used in such environment where the client uses the 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 logs into their mail box  through multiple devices like computer , laptops, smart phones 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 domain name into IP address.

DHCP ( Dynamic Host Cpnfiguration 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 the connection oriented protocol. The comnection is established between the application programs  and then the information are being exchanged between the them. It is also said to be 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 which is alternative to TCP.  It is considered to be connectionless and unreliable protocol. Unlike TCP, UDP doesnt 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 which works between layer 2 and layer 3 of 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 which is opposite of ARP.  RARP is responsible for resolving MAC address to IP version 4 address.

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