How the Internet Actually Works: Cables Under the Ocean and All

The internet is physical. Cables under the ocean, packets racing through routers, DNS translating names to addresses. Here is how it actually works.

It Starts With Cables Under the Ocean

The internet is, at its most physical, a network of cables — many of them running along the ocean floor. There are approximately 400 active submarine cable systems connecting continents, carrying over 95% of international data traffic. These cables are roughly the diameter of a garden hose, protected by steel wire and polyethylene, and they carry vast quantities of data as pulses of light through fiber optic strands. A typical transatlantic cable carries terabits of data per second.

When people talk about "the cloud," they mean servers sitting in data centers, connected to each other and to users through these cables. The cloud is physical. It has a location. It uses electricity. When a backhoe accidentally cuts a submarine cable — which happens — internet speeds between regions drop measurably, and engineers scramble to reroute traffic.

How Data Actually Travels: Packets

When you send an email or load a webpage, your data doesn't travel as a continuous stream. It's broken into small pieces called packets — typically 1,500 bytes each — which travel independently through the network and are reassembled at the destination. A single email might travel as dozens of packets, each potentially taking a different route through the network.

TCP/IP is the protocol suite that makes this work. IP (Internet Protocol) addresses each packet with source and destination addresses. TCP (Transmission Control Protocol) manages the reliable delivery — it tracks which packets arrived, requests retransmission of lost ones, and ensures packets are reassembled in the right order. When you watch a video, UDP (User Datagram Protocol) is often used instead — it sacrifices reliability for speed, accepting that some packets will be lost (better a slightly pixelated video than a stuttering one).

DNS: The Internet's Phone Book

When you type "goodpeoplemap.com" into a browser, your computer doesn't know the IP address (like 104.21.16.1) that corresponds to that name. It asks a DNS (Domain Name System) resolver — usually provided by your ISP or a service like Google (8.8.8.8) — which looks up the mapping in a hierarchically organized global database. This lookup takes milliseconds and happens for every website you visit.

DNS is also a significant security surface. DNS hijacking — redirecting name lookups to fraudulent IP addresses — is a common attack vector. DNSSEC (DNS Security Extensions) adds cryptographic verification but is not universally deployed.

Internet Exchange Points: Where the Internet Meets Itself

The internet is not one network; it's a network of networks. Internet Service Providers (ISPs), content networks (Netflix, Google), and academic networks connect to each other at Internet Exchange Points (IXPs) — physical locations where they hand traffic off between networks. The Amsterdam Internet Exchange (AMS-IX) processes over 10 terabits per second. These facilities are critical infrastructure; disruption to a major IXP cascades through the networks connected to it.

CDNs: Why Netflix Loads Fast

Content Delivery Networks (CDNs) like Cloudflare, Akamai, and Amazon CloudFront maintain copies of popular content in servers distributed globally — often within a few hundred kilometers of most internet users. When you load a video from Netflix, you're likely not connecting to a server in California; you're connecting to a CDN node nearby. This dramatically reduces latency and load on origin servers. CDNs now handle the majority of internet traffic by volume.

Fragile and Resilient at the Same Time

The internet was designed with resilience in mind — the ARPANET was partly funded by DARPA because a distributed network is harder to knock out than centralized systems. But resilience has limits. In 2021, a BGP (Border Gateway Protocol) misconfiguration at Facebook took down Facebook, Instagram, WhatsApp, and internal tools for about six hours. BGP is the protocol that routes traffic between networks; a misconfigured routing advertisement caused Facebook's network to become unreachable globally. The engineers couldn't even remotely access systems to fix it because their remote access tools were also down.

FAQ

Q: What is the difference between the internet and the World Wide Web?

A: The internet is the physical and logical infrastructure — cables, routers, protocols (TCP/IP, DNS). The World Wide Web is an application that runs on the internet — it's the system of hyperlinked documents accessed via HTTP/HTTPS using browsers. Email, voice calls (VoIP), file transfers, and streaming video are all internet applications distinct from the web. Tim Berners-Lee invented the web in 1989 at CERN; the internet as a concept predates it by decades (ARPANET was 1969).

Q: How does HTTPS protect data, and what does the padlock symbol actually mean?

A: HTTPS uses TLS (Transport Layer Security) to encrypt data between your browser and a website. The connection begins with a "handshake" where the browser verifies the website's identity via a certificate issued by a trusted Certificate Authority, then establishes an encrypted channel using asymmetric cryptography. The padlock symbol means the connection is encrypted and the certificate checks out — it does not mean the website itself is trustworthy or legitimate, only that your communication with it is private from eavesdroppers on the network.

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