Twenty-seven guides for a first computer networking course, in textbook chapter order: how the internet is built, the application layer, transport and TCP, then the network layer: routers, IP addressing, and the routing protocols that choose paths. Every calculation on every page was recomputed, and every guide ends with practice questions and worked solutions.
The order follows the top-down textbook most networking courses use. The Previous and Next links at the bottom of every guide follow this same order.
What gets tested in chapters 1 to 3, every formula on one sheet, the traps, and a seven-day plan.
The edge, the core, store-and-forward, and why FDM and TDM reserve capacity nobody may use.
d_trans = L/R versus d_prop = d/s, traffic intensity, and why the slowest link sets your speed.
Five layers, four packet names, and the nested envelopes that carry your data.
Client-server, sockets, and why an IP address alone cannot deliver a message.
Request line, status line, headers, blank line, body — and what every field is doing.
Why one costs 2 RTT per object and the other costs one for the whole page.
The four components, and why the purchase history is not in the cookie.
Three legs, three protocols, and the one leg SMTP never carries.
Root, TLD, authoritative, local — and writing A, NS, CNAME and MX without reversing them.
Getting a capture that actually contains HTTP, and reading every header field in it.
Ports, sockets, the 8-byte UDP header, and the checksum worked bit by bit with wraparound.
Checksums, ACKs, sequence numbers and timers, each added to fix one problem, plus the stop-and-wait math.
Sequence numbers count bytes, ACKs name the next byte wanted, and three duplicate ACKs trigger a resend.
The rwnd formula worked out, SYN / SYNACK / ACK with real numbers, and the FIN_WAIT and TIME_WAIT states.
One router moving one packet, versus the whole network choosing paths, and what the data and control planes are.
The four parts of a router, the three kinds of switching fabric, head-of-line blocking, output queues, buffer sizing and scheduling.
Each IPv4 header field in plain words, a worked checksum, and fragmentation offsets, flags and lengths computed step by step.
What a.b.c.d/x means, how to find the subnets in a network, and how to count and carve address blocks.
The four DHCP messages, where address blocks come from, and how NAT shares one public address by rewriting ports.
How a router picks one forwarding entry out of several matches, and how aggregation shrinks routing tables.
The fixed 40-byte IPv6 header, what was dropped from IPv4, how to shorten an address with ::, and how a tunnel carries IPv6 across IPv4-only routers.
How every router gets the whole map, and Dijkstra’s algorithm worked row by row on a six-router network.
The Bellman-Ford equation worked on three routers, why bad news travels slowly, and how poisoned reverse helps.
Why the Internet is split into autonomous systems, and how OSPF floods link states and runs Dijkstra inside each one.
How networks advertise prefixes to each other with AS-PATH and NEXT-HOP, and how BGP chooses among routes using policy first.
ICMP types and codes, how ping works, and how traceroute uses TTL-expired and port-unreachable messages to list every router on a path.
The free networking practice app has 500 written questions covering the whole course, from the internet’s edge and core through the application, transport, network and link layers to network security, every one with an explanation for every answer. Pick the topic you just read about.
Deep links into practice · Delay and throughput · HTTP · DNS · TCP congestion control · Subnets and CIDR · Dijkstra · CRC · RSA
Looking for a different class? Java · Python · Discrete Math · Security+ · Calculus, or the full guide catalog.
