Computer Networks
Layers, TCP/IP and what happens on a request.
Computer Networks is taught here in 14 lessons, running from Layered models and TCP/IP through to Network security: eavesdropping, MITM and DDoS. Each lesson takes one topic, shows the working code, and links onward to the next, so the course can be read straight through in order.
| Track | Computer Science Fundamentals |
| Lessons | 14 |
| Level | Beginner to intermediate |
| Reading time | about 3 hours |
| Prerequisites | Helpful, but not required: Data Structures |
Lessons
- Layered models and TCP/IPHow the OSI and TCP/IP models split network work into layers, and why encapsulation is the idea that lets every level be replaced independently.
- HTTP and DNS in practiceName resolution from stub resolver to authoritative server, the record types that matter, and how HTTP/1.1, HTTP/2 and HTTP/3 differ on the wire.
- One page request, end to endThe full path from typing a URL to a rendered page: DNS, TCP, TLS, HTTP, subresources, and where the milliseconds actually go.
- IP addressing, CIDR and subnettingIPv4 structure and the private ranges, CIDR notation and netmasks, how to compute a subnet by hand, gateways and broadcast addresses, and a first look at IPv6.
- Ports, sockets and the client-server modelWhat a port actually identifies, how ephemeral ports are assigned, what a listening and an accepted socket are, and the four-tuple that defines a connection.
- TCP in depth: handshake, windows and congestion controlThe three-way handshake and teardown, sequence and acknowledgement numbers, flow control windows, retransmission, slow start, and the latency consequences of each.
- UDP, QUIC and choosing reliabilityWhat UDP does and does not promise, why DNS and real-time media use it, how QUIC builds reliability on top of datagrams, and when TCP is the wrong tool.
- TLS and HTTPS: certificates and the handshakeWhat the handshake proves, how a certificate chain is verified, what SNI and ALPN do, why TLS 1.3 is one round trip, and what a browser checks before showing a lock.
- DNS deep dive: zones, records and DNSSECZone files and delegation, the record types that matter, TTL and caching behaviour, why propagation is really cache expiry, and what DNSSEC and DoH do and do not fix.
- Routing, NAT and gatewaysHow a router chooses a next hop, what a default route is, how NAT rewrites packets and what that breaks, and why traceroute shows fewer hops than there are routers.
- Network debugging toolkitping and mtr for reachability, dig for names, curl -v and openssl s_client for HTTP and TLS, ss for sockets, and tcpdump for when nothing else explains it.
- Proxies, load balancers and CDNsForward versus reverse proxies, layer 4 versus layer 7 balancing, health checks and sticky sessions, where TLS terminates, and how CDN caching rules actually behave.
- Wireless, mobile and the last mileWhy Wi-Fi and cellular behave differently from a wired link, how roaming changes an IP address, latency versus bandwidth, and what to expect from a mobile client.
- Network security: eavesdropping, MITM and DDoSSniffing and ARP spoofing on a shared segment, how a man in the middle works and how certificate pinning stops it, reflection attacks, and the defensive layers that actually help.
More in Computer Science Fundamentals
Algorithms Data Structures Operating Systems Character Encodings Hashing & Checksums Data Formats Dates & Time Regular Expressions
FAQ
How long does the Computer Networks course take?
It has 14 lessons, about 3 hours of reading. Expect roughly twice that if you type out and run every example.
Do I need prior experience for Computer Networks?
Not strictly. It helps to have read Data Structures first, because some lessons build on it, but every lesson explains its own assumptions.
What should I read after Computer Networks?
Continue with Operating Systems (14 lessons), the next course in Computer Science Fundamentals.