Searchable hosting and infrastructure glossary.
Domain Name System — translates human-readable domain names into IP addresses.
DNS is the internet phonebook. When you type google.com, DNS finds the server IP address.
Hierarchical distributed database. Recursive resolvers query root → TLD → authoritative nameserver. Uses UDP port 53; DNSSEC adds cryptographic verification.
Hypertext Transfer Protocol — the foundation of data communication on the web.
How browsers request web pages from servers and receive HTML back.
HTTP/1.1 uses persistent connections. HTTP/2 multiplexes streams over one TCP connection. HTTP/3 uses QUIC over UDP, eliminating head-of-line blocking.
HTTP Secure — HTTP encrypted with TLS/SSL certificates.
The padlock in your browser. Encrypts data so nobody can spy on your connection.
TLS 1.3 handshake completes in 1 RTT. Uses AEAD ciphers (AES-GCM, ChaCha20-Poly1305). HSTS preload lists enforce HTTPS-only access.
Cryptographic protocols that secure data in transit between client and server.
Encrypts the connection so passwords and credit cards are safe.
SSL is deprecated; TLS 1.2/1.3 is current. Uses X.509 certificates signed by Certificate Authorities. Forward secrecy via ephemeral ECDHE key exchange.
Content Delivery Network — geographically distributed servers that cache and deliver content.
Copies your website to servers worldwide so it loads fast everywhere.
Uses anycast routing, edge caching with TTL, origin shielding, and stale-while-revalidate. Major providers: Cloudflare, Akamai, AWS CloudFront, Fastly.
Virtual Private Server — a virtualized slice of physical server with dedicated resources.
Your own virtual computer on shared hardware with guaranteed RAM and CPU.
KVM and Xen provide hardware-level isolation. Hypervisor allocates vCPU, RAM, and disk I/O. Root access for custom software stacks.
Platform for developing, shipping, and running containerized applications.
Packages your app with everything it needs into a portable container.
Uses Linux namespaces (PID, NET, MNT) and cgroups. Images built in layers via Dockerfile. Docker Compose orchestrates multi-container apps.
Simple Mail Transfer Protocol — standard for sending email between servers.
The protocol that delivers your outgoing emails to recipients.
Uses port 587 (STARTTLS) or 465 (SMTPS). SPF, DKIM, and DMARC authenticate sending servers. MTA (Mail Transfer Agent) like Postfix handles routing.
Internet Message Access Protocol — syncs email across multiple devices.
Read email on phone and laptop — changes sync everywhere.
Port 993 with TLS. Server-side storage; client caches headers/bodies. IDLE extension for push notifications. Preferred over POP3 for business.
Mail Exchange DNS record — specifies which server receives email for a domain.
Tells the internet where to deliver emails for your domain.
Format: priority (lower=higher priority) + hostname. Multiple MX records provide failover. Must point to A/AAAA record, not CNAME (RFC 2181 exception for some providers).
Sender Policy Framework — DNS TXT record listing authorized email sending servers.
Proves your emails really come from your mail server, not a spammer.
v=spf1 include:_spf.google.com ~all. Maximum 10 DNS lookups. SPF alone fails on forwarded emails — combine with DKIM and DMARC.
DomainKeys Identified Mail — cryptographic email authentication via digital signatures.
Adds a digital signature to emails proving they were not tampered with.
RSA/Ed25519 key pair. Public key published in DNS TXT record. Signing happens at MTA. Verification at receiving server before spam scoring.
Domain-based Message Authentication — policy for handling failed SPF/DKIM checks.
Tells email providers what to do with fake emails pretending to be from your domain.
Policy: none (monitor), quarantine (spam folder), reject (block). Aggregate reports sent to rua= address. Requires aligned SPF or DKIM pass.
DNS Address record — maps a domain name to an IPv4 address.
Points your domain (example.com) to your server IP (93.184.216.34).
TTL controls cache duration. Multiple A records enable round-robin load balancing. Use AAAA record for IPv6 equivalent.
Canonical Name record — aliases one domain name to another.
Makes www.example.com point to the same place as example.com.
Cannot coexist with other record types on same name. Creates additional DNS lookup. Used for CDN CNAME (cdn.example.com → d123.cloudfront.net).
Time To Live — how long DNS resolvers cache a record before re-querying.
How long the internet remembers your DNS setting before checking again.
Measured in seconds. Lower TTL (300) before migrations. Higher TTL (86400) reduces DNS query load. Cached values persist during propagation.
Secure Shell — encrypted protocol for remote server administration.
Securely connect to your server from terminal: ssh user@server.com
Port 22 default. Key-based auth (Ed25519/RSA) preferred over passwords. Supports tunneling, SFTP file transfer, and agent forwarding.
File Transfer Protocol — upload/download files to web server.
Upload website files to your hosting server.
FTP (port 21) sends credentials in plaintext — avoid. SFTP (SSH File Transfer, port 22) is encrypted. FTPS adds TLS to FTP. Use SFTP or hosting file manager.
Popular open-source relational database used by WordPress and PHP applications.
Stores your website data — posts, users, products, settings.
InnoDB engine with ACID compliance. Port 3306. Replication for read scaling. MariaDB is a popular fork with enhanced features.
In-memory data store used for caching, sessions, and message queues.
Super-fast temporary storage that makes your website load much faster.
Key-value store with microsecond latency. Supports strings, hashes, lists, sets, sorted sets, pub/sub. Persistence via RDB snapshots and AOF logs.
High-performance web server and reverse proxy.
Software that serves your website to visitors — faster than Apache for high traffic.
Event-driven architecture handles 10,000+ concurrent connections. Used as reverse proxy, load balancer, and API gateway. Config in /etc/nginx/sites-available/.
Most widely used open-source web server software.
The software running on most shared hosting servers to deliver web pages.
Process/thread per connection model. .htaccess enables per-directory config without restart. mod_rewrite for URL rewriting. Often paired with mod_php or PHP-FPM.
Popular web hosting control panel for Linux servers.
Dashboard to manage domains, email, files, and databases without coding.
WHM (Web Host Manager) for server admin; cPanel for end users. Includes Softaculous auto-installer, JetBackup, and DNS zone editor.
Percentage of time a service is operational. SLA defines guaranteed uptime.
99.9% uptime means your site is down less than 9 hours per year.
Five nines (99.999%) = 5.26 min/year downtime. SLA credits compensate for breaches. Monitor with UptimeRobot, Pingdom, or StatusCake.
Amount of data transferred between server and visitors over a period.
How much traffic your hosting plan allows per month.
Measured in GB/month or TB/month. Includes all HTTP/HTTPS traffic. CDN reduces origin bandwidth. Overage may incur charges or throttling.
Distributed Denial of Service — overwhelms server with fake traffic from many sources.
Attackers flood your site with traffic to crash it and make it unavailable.
Layer 3/4 (volumetric SYN floods) vs Layer 7 (HTTP floods). Mitigated by CDN, rate limiting, WAF, and anycast scrubbing centers.
Web Application Firewall — filters malicious HTTP traffic to web applications.
Security shield that blocks hackers from exploiting your website.
Inspects request headers, body, and URL for OWASP Top 10 patterns. Cloudflare WAF, AWS WAF, ModSecurity. Custom rules for application-specific threats.
Container orchestration platform for automating deployment, scaling, and management.
Manages hundreds of Docker containers across multiple servers automatically.
Control plane (API server, etcd, scheduler) + worker nodes (kubelet). Declarative config via YAML manifests. CNCF graduated project.
Infrastructure as Code tool for provisioning cloud resources declaratively.
Define servers and networks in code files instead of clicking in dashboards.
HashiCorp HCL language. State file tracks resources. Plan/apply workflow. Providers for AWS, GCP, Azure, Cloudflare. Modules for reusability.
Free, automated Certificate Authority providing TLS certificates.
Free SSL certificates — add HTTPS to your site at zero cost.
ACME protocol automates domain validation via HTTP-01 or DNS-01 challenges. 90-day validity; auto-renew via Certbot. DV certificates only.
