Networking
Addresses, ports and handshakes - how machines find and talk to each other.
- 1Addresses and subnetsAn IPv4 address is 32 bits, and "/24" says how many of them name the network. Read a CIDR block bit by bit, then write a firewall rule that lets in one node's pods and nothing else.Runs in your browserOn your machine15 min+35 XP
- 2Ports, sockets and the handshakeA program listens on an address and a port, and TCP opens a connection in three packets. Learn to tell a fast "refused" from a slow timeout, and fix the classic "works on my machine" bind.Runs in your browserOn your machine16 min+40 XP
- 3How a name becomes an addressA resolver walks from the root to the one server that knows the answer, then remembers it for exactly as long as the TTL says. Move a site to a new server without stranding anyone in a cache.Runs in your browserOn your machine16 min+40 XP
- 4Load balancers and proxiesOne address, many servers. Watch round robin feed a crashed backend, watch least connections make it worse, then fix it with health checks - and learn why only an L7 proxy can route by path.Runs in your browserOn your machine16 min+40 XP
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