1. Web Protocols

HTTP (80) → Transfers web pages (stateless, GET/POST).
HTTPS (443) → Secure HTTP using SSL/TLS.
🗝️ Tip: HTTP = highway (80 lanes), HTTPS = lock added (443).

2. File Transfer Protocols

FTP (20-data / 21-control) → Upload/download files.
SFTP (22) → Secure FTP via SSH.
🗝️ Tip: 20 & 21 = file in 2 parts (data + control).

3. Email Protocols

SMTP (25 / 587) → Send mail (push).
POP3 (110 / 995) → Download mail (delete from server).
IMAP (143 / 993) → Sync mail (keeps on server).
🗝️ Tip:
SMTP → Send (25 is mail on its way 📮).
POP3 → Post office, 1-to-1 mailbox (110).
IMAP → Multiple devices sync, like tree branches (143).

4. Name & Addressing Protocols

DNS (53) → Converts domain → IP.
- Records: A (IPv4), AAAA (IPv6), MX (mail).
DHCP (67 server / 68 client) → Assigns IP automatically.
🗝️ Tip: DNS = “5-3 letters in a domain.” DHCP = 67 gives, 68 receives.

5. Remote Access Protocols

Telnet (23) → Remote access, NOT secure.
SSH (22) → Secure login, replaces Telnet.
RDP (3389) → Remote desktop (Windows).
🗝️ Tip: SSH = Secure 22, Telnet = 23 (tele).

6. Network Management Protocols

SNMP (161 manager / 162 agent) → Manage routers, switches.
LDAP (389) → Directory access (user authentication).
🗝️ Tip: SNMP → 161 boss asks, 162 agent replies.

7. Quick Port Summary Table (Must Memorize 🚨)

Port	Protocol	Purpose / Mnemonic
20/21	FTP	File transfer (20=data, 21=control)
22	SSH / SFTP	Secure remote login
23	Telnet	Insecure remote access
25 / 587	SMTP	Sending emails (push)
53	DNS	Name → IP
67/68	DHCP	Auto IP (67 server, 68 client)
80	HTTP	Web browsing
110	POP3	Retrieve emails (download & delete)
143	IMAP	Retrieve emails (sync)
161/162	SNMP	Network management
389	LDAP	Directory services
443	HTTPS	Secure web
3389	RDP	Remote desktop

✅ Exam Tip:

Questions often ask “Match protocol to port” or “Which protocol is used for X?”
Focus on FTP, HTTP/HTTPS, SMTP, DNS, DHCP, POP3, IMAP, SNMP, SSH, Telnet, RDP – these are most common.

MCQ

1. What is the primary purpose of HTTP?
a) File transfer between client and server
b) Transmitting web pages and resources
c) Resolving domain names to IP addresses
d) Monitoring network devices

Answer: b) Transmitting web pages and resources

2. Which protocol uses port 53 by default?
a) SMTP
b) FTP
c) DNS
d) HTTP

Answer: c) DNS

3. Which protocol is used for sending emails?
a) POP3
b) SMTP
c) IMAP
d) FTP

Answer: b) SMTP

4. Which of the following is a secure alternative to Telnet?
a) SSH
b) SNMP
c) HTTP
d) FTP

Answer: c) SSH

5. What is the default port for FTP data transfer?
a) 25
b) 20
c) 22
d) 110

Answer: b) 20

6. Which DNS record maps a domain name to an IPv4 address?
a) AAAA Record
b) CNAME Record
c) MX Record
d) A Record

Answer: d) A Record

7. What is the primary purpose of SNMP?
a) Transfer files between systems
b) Manage and monitor network devices
c) Send and receive emails
d) Resolve domain names into IP addresses

Answer: b) Manage and monitor network devices

8. Which protocol ensures secure communication over the web?
a) HTTPS
b) FTP
c) Telnet
d) SMTP

Answer: a) HTTPS

9. What is the key function of IMAP in email systems?
a) Sending emails from a client
b) Storing and retrieving emails from a server
c) Resolving email domains to IP addresses
d) Deleting emails after downloading

b) Storing and retrieving emails from a server

10. Which protocol is stateless and operates on port 80?
a) FTP
b) HTTP
c) SMTP
d) DNS

Answer: b) HTTP

11. Which port is used by HTTPS for encrypted communication?
a) 22
b) 443
c) 80
d) 110

Answer: b) 443

12. Which of the following is a push protocol?
a) FTP
b) SMTP
c) HTTP
d) IMAP

Answer: b) SMTP

13. Which protocol is primarily used to upload files to a web server?
a) FTP
b) DNS
c) Telnet
d) SMTP

Answer: a) FTP

14. What type of DNS record is used for email servers?
a) MX Record
b) CNAME Record
c) A Record
d) AAAA Record

Answer: a) MX Record

15. Which protocol uses port 110 by default?
a) IMAP
b) POP3
c) SMTP
d) FTP

Answer: b) POP3

16. What protocol resolves www.google.com into an IP address?
a) SNMP
b) FTP
c) DNS
d) HTTP

Answer: c) DNS

17. Which protocol uses MIB to store and retrieve management data?
a) Telnet
b) SNMP
c) IMAP
d) FTP

Answer: b) SNMP

18. Which email protocol allows syncing across multiple devices?
a) POP3
b) SMTP
c) IMAP
d) Telnet

Answer: c) IMAP

19. What is the purpose of a CNAME record in DNS?
a) Redirecting traffic from one domain to another
b) Mapping IPv6 addresses
c) Storing mail server information
d) Managing session layers

Answer: a) Redirecting traffic from one domain to another

20. Which protocol handles the encryption of web pages?
a) HTTPS
b) HTTP
c) FTP
d) Telnet