Unit 12.4A · Term 4 (Revision)

Protocols Revision

This revision lesson covers network protocols — the rules that govern communication between devices. You'll also review IP addresses (format, public vs private) and their role in network communication.

Learning Objectives

  • 11.6.3.1 Explain the role of protocols (HTTP, FTP, POP3, SMTP, HTTPS, FTPS)
  • 11.6.3.2 Explain the format of an IP address and how it is associated with a device
  • 11.6.3.3 Explain the difference between public and private IP addresses

Lesson Presentation

12.4A-revision-protocols.pdf · Slides for classroom use

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Key Concepts Review

Network Protocols

Protocol Full Name Purpose Port
HTTP HyperText Transfer Protocol Transfer web pages (unsecured) 80
HTTPS HTTP Secure Encrypted web page transfer (SSL/TLS) 443
FTP File Transfer Protocol Upload/download files 21
FTPS FTP Secure Encrypted file transfer 990
SMTP Simple Mail Transfer Protocol Sending emails 25/587
POP3 Post Office Protocol v3 Receiving emails (downloads to device) 110
IMAP Internet Message Access Protocol Receiving emails (stays on server) 143

IP Address Format

1 IPv4 Address

Format: xxx.xxx.xxx.xxx (4 octets, dotted decimal) Example: 192.168.1.100 Each octet = 8 bits → range 0–255 Total address space = 32 bits → ~4.3 billion addresses IPv6: 128-bit addresses written in hexadecimal Example: 2001:0db8:85a3:0000:0000:8a2e:0370:7334

Public vs Private IP

Feature Public IP Private IP
Visibility Visible on the Internet Only within local network (LAN)
Assigned by ISP (Internet Service Provider) Router / DHCP server
Uniqueness Globally unique Unique only within LAN (can repeat across networks)
Ranges Any address not in private ranges 10.x.x.x / 172.16–31.x.x / 192.168.x.x
NAT Not needed Requires NAT to access the Internet

Revision Tasks

Remember

List 6 network protocols and explain the purpose of each.

Understand

Explain the difference between HTTP and HTTPS. Why is HTTPS important?

Apply

Given the IP address 192.168.0.5, determine if it is public or private and explain how you know.

Analyze

Compare POP3 and IMAP. When would you use each? Which is better for accessing email from multiple devices?

Self-Check Quiz

Q1: What protocol is used to send emails?

SMTP (Simple Mail Transfer Protocol) — it handles sending/outgoing emails from a mail client to a mail server.

Q2: Is 10.0.0.1 a public or private IP address?

Private — the 10.x.x.x range is reserved for private networks. It cannot be used directly on the Internet.

Q3: How many bits are in an IPv4 address?

32 bits — divided into 4 octets (8 bits each), written in dotted decimal notation (e.g., 192.168.1.1).