TCP/IP: fundamentals and diagnosis

Objectives and progression

A technical-skill course with six modules, explained decisions, and fictional APS cases. Interpret subnets, routes, TCP states, flow, PMTU, and Linux contexts. References TCP RFC 9293 and IPv6 RFC 8200 with RFC 9673 update. Internal assessment of 24 decisions in 60 minutes. This is not an official certification; captures and outputs are illustrative, with no commands or labs executed.

Audience: APS L2/L3 teams, Linux administrators, and technical infrastructure managers.

Prerequisites: System and application fundamentals; exercises provide required addresses and evidence.

300 estimated study minutes

• Interpret subnets, bindings, and context before testing a service.
• Connect more-specific prefixes, policy, and local neighbours.
• Distinguish connection, byte delivery, and application outcome.
• Relate TCP states and receive pressure to application behavior.
• Explain why small requests can work while larger transfers fail.
• Choose comparable observations and validate the result after change.

Modules

1. Addresses, prefixes, and scope
2. Routes and next-hop resolution
3. Transport, acknowledgement, and messages
4. States, queues, and flow control
5. MTU, ICMP, and size-dependent failures
6. Diagnosis in the application context

Continue learning

Technical assessments

• DNS
• CompTIA Network+
• Cisco CCNA
• Linux Administration

References and version

DR TCP/IP 2026-09; TCP RFC 9293; IPv6 RFC 8200 with RFC 9673 update; Linux socket and iproute2 guidance

• TCP base specification: RFC 9293 · 2026-09-30
• IPv6 base specification: RFC 8200 · 2026-09-30
• CIDR and longest-prefix routing: RFC4632 · 2026-09-30
• Linux TCP sockets and receive queue · 2026-09-30
• Socket inspection with ss · 2026-09-30
• Linux route selection and route get · 2026-09-30
• IPv6 Path MTU Discovery: RFC8201 · 2026-09-30
• ARP: RFC826 · 2026-09-30
• IPv6 Neighbor Discovery: RFC4861 · 2026-09-30
• Linux routing policy rules · 2026-09-30
• Linux IPv4 sockets and addresses · 2026-09-30
• IPv6 Hop-by-Hop update: RFC 9673 · 2026-09-30
• IPv4 Path MTU Discovery: RFC1191 · 2026-09-30
• ICMP: RFC792 · 2026-09-30
• ICMPv6: RFC4443 · 2026-09-30
• Linux UDP datagrams · 2026-09-30
• Linux socket interfaces and binding · 2026-09-30
• Linux neighbour states and bindings · 2026-09-30
• Documentation IPv4 address blocks: RFC5737 · 2026-09-30
• Linux IP sysctl and bindv6only · 2026-09-30
• Linux network namespace isolation · 2026-09-30
• IPv6 scoped addresses: RFC4007 · 2026-09-30