Hosting, CDN & Edge

Busted

• Anycast routing / point of presence (PoP)One IP address announced from many edge locations, so internet routing sends each visitor toward a nearby point of presence.
• AutoscalingCapacity that follows demand: the platform adds instances when traffic climbs and removes them when it drops, with nobody watching.
• Bandwidth throttlingDeliberately capping how fast data flows to one client, so a single heavy download cannot eat the pipe everyone else shares.
• Bare-metal server / virtual private server (VPS)Bare metal rents you the whole physical machine; a VPS rents you an isolated virtual slice of a shared machine.
• Brotli / gzip compressionSqueezing text responses before they cross the wire, so the browser downloads a fraction of the bytes and unpacks them on arrival.
• Cache hit / cache missA hit means the nearby cache already had the answer. A miss means it had to go ask your real server, and the visitor feels the wait.
• Cache invalidation / purgeTelling the caches to throw away their copy of something you changed, so the next visitor gets the new version instead of the old one.
• Cache keyThe exact identity a cached response is stored under. Same key, same copy served, which is great until two pages collide.
• Cache stampede / thundering herdThe traffic pileup when a popular cache entry expires and many requests hit the origin together to rebuild the same thing.
• Cache warmingFetching important pages before visitors arrive, so the cache pays the first slow trip to origin instead of a real person.
• Cache-Control / cache TTLThe header that tells browsers and CDNs how long they may keep a copy before checking with you again.
• CDN (content delivery network)A worldwide network of caching servers that keeps copies of your files near your visitors, so downloads come from the next city.
• Cold startThe extra delay when a serverless function has to boot from scratch because nothing was already running to take your request.
• Compute instance / virtual machineA rented virtual server that stays yours to configure, patch, run, and monitor until you shut it down.
• Container image / containerAn image is your app frozen with its whole environment; a container is one running copy of it. The cure for 'works on my machine'.
• DNS propagationThe wait after a DNS change while resolvers worldwide let their cached old answer expire. Almost nothing spreads, it just expires.
• DNS records (A, AAAA, CNAME)The rows in your domain's settings that say where the name points: A and AAAA to an IP address, CNAME to another hostname.
• DNS TTLThe number of seconds DNS resolvers may keep an answer before asking again. It sets how long old records can linger after a change.
• Edge cache hit ratioThe percentage of requests answered by the edge cache instead of your real server. Higher usually means less origin work.
• Edge functionServer code that runs in whatever datacenter is closest to the visitor, instead of in one machine far away.
• Edge KV / distributed key-value storeA small key-to-value database copied across regions so edge code can read settings near the visitor.
• Edge middlewareTiny code that runs at the CDN on every request, before your page does, to redirect, rewrite, or tag the visitor.
• Edge runtime vs Node.js runtimeEdge runtime is a lean Web-API V8 sandbox that starts almost instantly. Node runtime is a full Node process with npm, fs, and sockets.
• Egress feesProviders charge for data leaving their network. Storing the file is cheap; letting the internet download it is where the bill comes from.
• Ephemeral filesystemTemporary local disk that may be wiped whenever a function, container, or hosted instance is replaced.
• FailoverAutomatically sending new traffic to a healthy backup when the primary server or region stops working.
• Health checkA small repeated test that tells a load balancer whether a server is healthy enough to keep receiving traffic.
• HTTP/3 / QUICThe newest HTTP transport, built on QUIC and UDP for quicker secure setup and fewer stalls when packets are lost.
• Image CDN / on-the-fly transformsAn image URL that takes orders: ask for 640px wide AVIF and the CDN renders that version from your one original, then caches it.
• Immutable asset / content hashingBaking a hash of a file's contents into its filename, so it can be cached forever and any change ships as a brand new URL.
• Load balancerOne address in front of many servers, handing each request to whichever one is healthy and least busy. Visitors just see a single site.
• Nameserver (NS record)The authoritative server that holds a domain's DNS answers. NS records tell the internet which provider is in charge of them.
• Object storage / storage bucketA giant flat drive in the cloud: you save a file under a key and fetch it back by URL. No folders, no filesystem, no server to run.
• Origin serverThe real machine your content actually lives on. The CDN is a crowd of copies; the origin is the one that can answer when they cannot.
• Origin shieldA shared cache between all the edge locations and your real server, turning many worldwide misses into one origin fetch.
• PaaS vs IaaSPaaS hands you a deploy button and manages the machine; IaaS hands you the raw machine and the pager. You trade control for chores.
• Persistent volumeA durable disk mounted into a VM or container that keeps its data when the process or instance is replaced.
• Region / multi-regionThe physical geography your compute and database actually sit in, and whether you run copies in more than one of them.
• Request timeout / execution limitThe clock that decides when a slow request stops waiting or when a hosted function is forcibly stopped.
• Reverse proxyA server that sits in front of your servers, taking every request and deciding which backend answers it.
• Rewrite vs redirectA redirect sends the browser elsewhere and the URL changes. A rewrite quietly serves other content while the URL stays put.
• Serverless computing / functions as a service (FaaS)You upload a function, the platform runs it on demand and bills per call. Servers exist, but babysitting them is not your job.
• Stale-while-revalidateA caching rule that hands over the cached copy instantly, then fetches a fresh one in the background for the next visitor.
• Surrogate key / cache tagA label shared by related cached pages, so one purge can clear every page showing the same product, post, or category.
• TLS certificate / TLS terminationThe file that earns your site the padlock, plus the question of which machine actually decrypts the traffic: the edge or your server.
• Vary headerThe response header that tells a cache to keep separate copies of one URL for different encodings, languages, or device types.
• Vertical vs horizontal scalingVertical scaling makes one server bigger; horizontal scaling adds more servers and shares the work between them.
• Wildcard domain / subdomain routingSending every customer subdomain to one deployment, then using the hostname to decide which customer's site to show.

The territory

28 core terms mapped for this field, ranked by how often builders reach for them. Each one is a future entry. Want to bust one? One entry, one file, one pull request.

• CDN (content delivery network)global cache network serving files from nearby locations"make images load fast worldwide" · "copies of my site everywhere"
• Edge functioncode that runs in a datacenter near the user"run my code close to people" · "serverless but nearer"
• Cache invalidation / purgeforcibly clearing stale cached copies after a change"site still shows the old version" · "how do I force a refresh"
• Origin serverthe true source the CDN pulls content from"the real server behind the cache" · "where files actually live"
• Cache hit / cache misswhether edge cache serves a request or forwards it to origin"did it come from the cache" · "why is it still hitting my server"
• Cache-Control / cache TTLheader and lifetime telling caches how long to keep content"how long before it refreshes" · "expiry setting"
• DNS records (A, AAAA, CNAME)mappings that point a domain at a server"connect my domain to the host" · "point the name somewhere"
• DNS propagationdelay before DNS changes become visible across recursive resolvers"why isn't my domain working yet" · "waiting for DNS to update"
• TLS certificate / TLS terminationthe padlock, and where encryption is decrypted"make it https" · "SSL certificate setup" · "HTTPS termination"
• Cold startdelay when a serverless function boots after idling"first visit is always slow" · "spins up before responding"
• Serverless computing / functions as a service (FaaS)run code without managing servers, billed per invocation"no server to babysit" · "just upload the function"
• Reverse proxyserver in front that routes and caches requests to backends"thing that sits in front" · "traffic director"
• Region / multi-regionwhich geography your compute and data live in"servers in Europe too" · "closer to my users"
• Stale-while-revalidateserve old copy instantly while fetching a fresh one"instant but updates behind the scenes"
• Cache keythe exact identity a cached response is stored under"why are two pages sharing one cached copy" · "what makes a cache entry unique"
• Edge middlewaretiny code intercepting requests before they hit a route"redirect or rewrite before the page loads"
• Rewrite vs redirectserve other content silently vs send browser elsewhere"keep the URL but show something else"
• Edge runtime vs Node.js runtimelimited fast V8 sandbox vs full server runtime"this npm package won't run on the edge" · "which runtime do I pick"
• Container image / containerpackaged app plus environment, and the running copy of it"ship the whole environment" · "Docker thing"
• PaaS vs IaaSmanaged platform versus raw infrastructure you run yourself"managed hosting or my own server" · "how much infra do I have to manage"
• Object storage / storage bucketflat file store for assets, addressed by key"somewhere to dump images and videos" · "S3-style storage"
• Egress feescharges for data leaving the provider's network"why is my bandwidth bill huge"
• Load balancerspreads incoming traffic across multiple servers"share the traffic out"
• Autoscalingcapacity grows and shrinks with demand automatically"handles a traffic spike by itself"
• Immutable asset / content hashingfilenames change on change, so caching is forever"cache my JS and CSS forever" · "hashed filenames"
• Brotli / gzip compressionshrinking text responses in transit"turn on compression" · "make my responses smaller"
• Image CDN / on-the-fly transformsresize, crop, reformat images at request time"auto-resize images per device"
• Bandwidth throttlingcapping data throughput per client or connection"cap how much data one client pulls" · "slow down heavy downloads"

Deeper in the field

• Vary header cache splits by device, language, or encoding
• Surrogate key / cache tag label letting you purge groups of pages at once
• Cache warming preloads content to avoid initial cache misses
• Edge cache hit ratio share of requests served without touching origin
• Origin shield extra cache layer protecting the origin from stampedes
• Cache stampede / thundering herd many misses hit origin at once when cache expires
• Anycast routing / point of presence (PoP) one IP routed to the nearest edge location
• HTTP/3 / QUIC newer transport with faster connection setup
• DNS TTL how long resolvers cache a DNS answer before refreshing
• Nameserver (NS record) delegates a domain's DNS authority to another provider
• Wildcard domain / subdomain routing one deploy serving many customer subdomains
• Health check probe deciding whether an origin should receive traffic
• Failover routes traffic to a healthy backup when the primary fails
• Request timeout / execution limit maximum time a request or function may run
• Vertical vs horizontal scaling bigger machine vs more machines
• Compute instance / virtual machine persistent virtual server the builder provisions and manages
• Bare-metal server / virtual private server (VPS) rented physical machine versus a virtualized slice of one
• Ephemeral filesystem local files may vanish when an instance restarts or moves
• Persistent volume durable disk attached to a hosted instance or container
• Edge KV / distributed key-value store small globally replicated data readable at the edge