Learn about networking and domains
Domains, DNS, SSL and CDNs connect your app to people. Learn how each piece works and how to fix the most common errors.
Featured
- ConceptsWhat is a load balancer and how does it work?A load balancer spreads incoming requests across several servers. Learn how it works, the main algorithms, layer 4 vs 7, and a working nginx example.
- ConceptsDNS records explained: A, CNAME, MX, TXTDNS records are the instructions in a zone that tell the internet where a name points. Learn A, AAAA, CNAME, MX, TXT, NS and CAA with examples and dig commands.
- How-to guidesHow to point a domain to your server or appTo point a domain to your server or app, create a CNAME (or A) record in your registrar's DNS panel. Steps, how to test it, and common mistakes.
Concepts9
- What is a load balancer and how does it work?A load balancer spreads incoming requests across several servers. Learn how it works, the main algorithms, layer 4 vs 7, and a working nginx example.
- DNS records explained: A, CNAME, MX, TXTDNS records are the instructions in a zone that tell the internet where a name points. Learn A, AAAA, CNAME, MX, TXT, NS and CAA with examples and dig commands.
- What is SSL/TLS?SSL/TLS is the protocol that encrypts the connection between a browser and a server and proves the site is genuine. Learn how it works and what a certificate is.
- What is a CDN and what is it used for?A CDN is a network of servers around the world that keeps copies of your content and answers from near the visitor. Learn how it works, what to cache and its limits.
- What is DNS and how does it work?DNS is the system that translates domain names into IP addresses. Learn how a query moves through resolver, root and authoritative servers, plus caching and TTL.
- What is a reverse proxy?A reverse proxy is a server that receives client requests and forwards them to your app. Learn how it works, what it is for, and a working nginx example.
- What is a subdomain?A subdomain is a prefix before your main domain, like api.example.com. Learn how it works in DNS, how to create one, and when to pick it over a subfolder.
- IPv4 vs IPv6 and static IPs for developersIPv4 uses 32-bit addresses and IPv6 uses 128-bit ones. Learn the difference, what a static IP is, and why pointing a domain by name is usually better.
- Latency and ping: why server location mattersLatency is the time data takes to travel between you and a server and back. Learn what ping is, what adds latency, how to measure it with curl and how to cut it.
How-to guides5
- How to point a domain to your server or appTo point a domain to your server or app, create a CNAME (or A) record in your registrar's DNS panel. Steps, how to test it, and common mistakes.
- Cache-Control headers explainedCache-Control is the HTTP header that sets how long browsers and CDNs keep a response. Learn max-age, no-cache, immutable and ready-made recipes for each file type.
- How to use a custom domain for your appTo use a custom domain, add it to your host and create the DNS records the host gives you. Learn the steps, www vs root, HTTPS and common errors.
- Free SSL certificates: how Let's Encrypt worksLet's Encrypt issues SSL/TLS certificates at no cost, automatically, through the ACME protocol. Learn the validation challenges, renewal and how to issue your own.
- Load balancing algorithms explainedLoad balancing algorithms decide which server gets each request. Learn round robin, least connections, IP hash and consistent hashing, with nginx config and code.
Problems and errors4
- DNS propagation: why it takes so long and how to checkDNS propagation is the time caches take to drop an old record and fetch the new one. Learn how TTL works, why you still see the old site, and how to check with dig.
- SSL certificate errors: invalid, expired and handshake failuresInvalid, expired or 'not secure' SSL certificate? Learn the causes of certificate and handshake errors, how to diagnose them with openssl and curl, and the fix.
- DNS_PROBE_FINISHED_NXDOMAIN: what it meansDNS_PROBE_FINISHED_NXDOMAIN means the DNS server answered that the domain does not exist. Learn the causes, how to diagnose with dig, and how to fix each one.
- Load balancer timeouts and errors explainedA 504 means the load balancer gave up waiting for your app; a 502 means it got a bad reply. Learn each timeout, how to diagnose it and how to fix it.
Costs3
- How much does a CDN cost?A CDN costs from zero to hundreds of dollars a month, depending on traffic, visitor region and requests. See how to estimate the bill and the hidden costs.
- Do you need to pay for an SSL certificate?Free DV certificates encrypt just as strongly as paid ones. See what actually differs (validation, warranty, support) and when paying for a certificate makes sense.
- How much does a domain name cost?A .com adds up wholesale, an ICANN fee and registrar margin, and a .com.br has a fixed yearly price at Registro.br. See what sets the price and why renewals jump.
Comparisons3
- Domain vs hosting: what's the differenceA domain is the text address of your site; hosting is the server it runs on. See what each one does, where to buy them and how DNS connects the two.
- HTTP vs HTTPS: why browsers say 'not secure'HTTPS is HTTP inside an encrypted TLS connection. See the differences, why browsers label HTTP sites 'not secure', and how to migrate your site safely.
- A record vs CNAME: which one to useAn A record points a name to an IP address and a CNAME points it to another name. See the differences, the root domain rule, the MX conflict and when to use each.
Which to choose3
- What TTL should you use for DNS records?For most DNS records, a TTL of 300 to 3600 seconds balances speed and flexibility. See the right value for each record type and what to set before a migration.
- Which domain extension to choose: .com, .dev, .app or a country codeFor a global audience, .com is the safest choice; for one country, its country code. Learn when .dev and .app make sense and what changes for SEO, price and HTTPS.
- Does a small website need a CDN?A small site usually benefits from a CDN, but the gain depends on where your visitors are and what the site serves. See the criteria and when to skip one.