Why the Internet chops packets into pieces when they're too big—and why this seemingly elegant solution creates more problems than it solves.
Every packet you send into the Internet is a guess about what will fit. Path MTU Discovery is how your device learns the shape of the pipe—by watching what breaks.
Every TCP sender constantly asks the same question: how fast can I go without breaking things for everyone else? This is how congestion control keeps billions of connections from collapsing the Internet.
NAT broke the Internet's original promise that every device could both send and receive. Here's exactly how it works, why it persists, and how protocols like STUN and TURN punch through it.
Recursive queries delegate the work: 'Find this for me.' Iterative queries maintain control: 'Point me in the right direction.' Understanding this division of labor reveals how DNS actually functions.
IPsec is armor retrofitted onto a protocol that assumed trust. It authenticates, encrypts, and protects IP packets—making VPNs possible and letting networks pretend the Internet isn't hostile.
GRE wraps packets inside other packets, letting them cross networks that would otherwise reject them. No encryption, no authentication—just a disguise that makes the impossible route possible.
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