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L1.3 — Network Layer #1 covers the fundamentals of the Internet Layer (Layer 3), focusing on IP addressing with IPv4 and IPv6, packet routing principles, and the protocols that enable internetworking across networks.

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📋 At a Glance

• [ ] Review the role and position of the Internet Layer in the TCP/IP stack
• [ ] Understand packet switching, connectionless operation, and best-effort delivery
• [ ] Master IPv4 header structure and field purposes (TTL, fragmentation, checksums)
• [ ] Learn IPv4 addressing limitations and exhaustion timeline
• [ ] Understand NAT operation, benefits, and limitations
• [ ] Study IPv6 header structure and key improvements over IPv4
• [ ] Practice IPv6 address shortening conventions
• [ ] Review global IPv6 adoption statistics and deployment challenges
• [ ] Compare IPv4 vs IPv6 fragmentation approaches
• [ ] Understand ICMP's role in error reporting and diagnostics

1. Internet Layer Fundamentals

Layer Position and Purpose

The Internet Layer sits as Layer 3 in the TCP/IP model (equivalent to Network Layer in OSI). Its primary responsibilities include:

• Unique addressing - Providing globally unique IP addresses (ideally)
• Next-hop routing - Determining where to forward packets
• Internetworking - Connecting different networks together