1. File Transfer Protocol (FTP) – Port 21
Description: FTP is used for transferring files between a client and a server on a computer network.
Example: A web designer uploads updated HTML files to their client’s website hosting server.
2. Secure Shell (SSH) – Port 22
Description: SSH provides a secure channel over an unsecured network, commonly used for remote command-line access and data communication.
Example: A system administrator securely logs into a remote server to perform maintenance tasks from their home office.
3. Telnet – Port 23
Description: Telnet provides a bidirectional interactive text-oriented communication facility using a virtual terminal connection.
Example: A network technician uses Telnet to check the status of a router (though SSH is now preferred for security reasons).
4. Simple Mail Transfer Protocol (SMTP) – Port 25
Description: SMTP is used for sending and routing email between mail servers.
Example: When you send an email from your work account to a client, SMTP ensures it’s delivered to the recipient’s mail server.
5. Domain Name System (DNS) – Port 53
Description: DNS translates human-readable domain names into IP addresses.
Example: When you type “www.wikipedia.org” into your browser, DNS translates this to the corresponding IP address so your computer can locate the website.
6. Dynamic Host Configuration Protocol (DHCP) – Server Port 67, Client Port 68
Description: DHCP automatically assigns IP addresses and other network configuration parameters to devices on a network.
Example: When you connect your laptop to a new Wi-Fi network, DHCP automatically assigns it an IP address without any manual configuration.
7. Hypertext Transfer Protocol (HTTP) – Port 80
Description: HTTP is the foundation of data communication on the World Wide Web.
Example: When you browse a news website, your browser uses HTTP to request and receive the web pages from the server.
8. Post Office Protocol 3 (POP3) – Port 110
Description: POP3 is used by email clients to retrieve emails from a mail server.
Example: Your email app uses POP3 to download new emails from the server to your device, allowing you to read them offline.
9. Internet Message Access Protocol (IMAP) – Port 143
Description: IMAP allows email clients to access emails stored on a remote mail server.
Example: You check your work emails on both your smartphone and laptop. IMAP keeps them synced across both devices.
10. HTTP Secure (HTTPS) – Port 443
Description: HTTPS is a secure version of HTTP, using encryption for secure communication.
Example: When you log into your online banking portal, HTTPS ensures that your login credentials and financial data are encrypted.
11. Remote Desktop Protocol (RDP) – Port 3389
Description: RDP provides a graphical interface for connecting to another computer over a network connection.
Example: An IT support technician uses RDP to access and troubleshoot a user’s computer from their own workstation.
12. Transmission Control Protocol (TCP)
Description: TCP provides reliable, ordered, and error-checked delivery of data between applications running on hosts communicating over an IP network.
Example: When you download a large file, TCP ensures all parts of the file arrive correctly and in the right order.
13. User Datagram Protocol (UDP)
Description: UDP uses a simple connectionless communication model with a minimum of protocol mechanisms.
Example: During a video call, UDP is often used to transmit audio and video data, prioritizing speed over perfect reliability.
14. Address Resolution Protocol (ARP)
Description: ARP is used for discovering the link layer address (e.g., MAC address) associated with a given internet layer address (IP address).
Example: When your computer needs to send data to another device on your local network, it uses ARP to find that device’s MAC address.
15. Reverse ARP (RARP)
Description: RARP is used to obtain an IP address for a given link layer address (like a MAC address).
Example: A diskless workstation uses RARP to request its IP address from a network administrator’s server.
16. Network Time Protocol (NTP)
Description: NTP is used to synchronize the clocks of computer systems over packet-switched networks.
Example: A company uses NTP to ensure all its computers and servers have the exact same time, crucial for coordinating activities and logging events accurately.
17. Media Transfer Protocol (MTP)
Description: MTP allows media files to be transferred automatically to and from portable devices.
Example: When you connect your smartphone to your computer, MTP enables you to easily transfer photos and music between the devices.
18. Secure File Transfer Protocol (SFTP)
Description: SFTP provides file access, file transfer, and file management over a secure connection.
Example: A financial analyst securely transfers sensitive company reports to an external auditor using SFTP.
19. Secure Socket Layer (SSL) / Transport Layer Security (TLS)
Description: SSL/TLS protocols provide communication security over a computer network.
Example: When you make an online purchase, SSL/TLS ensures that your credit card information is encrypted as it’s sent to the merchant.
20. Point to Point Protocol (PPP)
Description: PPP provides a standard way to transport multi-protocol datagrams over point-to-point links.
Example: In the early days of the internet, PPP was commonly used for dial-up internet connections.
21. Network News Transfer Protocol (NNTP)
Description: NNTP is used for distributing, inquiring, retrieving, and posting news articles.
Example: Users access and post to Usenet newsgroups using NNTP.
22. Internet Control Message Protocol (ICMP)
Description: ICMP is used by network devices to send error messages and operational information.
Example: When you use the “ping” command to check if a website is reachable, you’re using ICMP.
23. Internet Group Management Protocol (IGMP)
Description: IGMP is used by IP hosts to report their multicast group memberships to routers.
Example: When multiple users in an office stream the same live webinar, IGMP helps manage the efficient delivery of this multicast stream.
24. Gateway to Gateway Protocol (GGP)
Description: GGP was an early internet protocol used for exchange of routing information between gateways.
Example: In the early internet, GGP was used to share routing information between major network gateways, helping data find efficient paths across the network.