Glossary

Quick-reference definitions for technical terms used across the Console9 Wiki.

A

A record— A DNS record type that maps a domain name to an IPv4 address. The A record is the most common DNS query type. See the dig article.

AAAA record— A DNS record type that maps a domain name to an IPv6 address. The AAAA record is the IPv6 equivalent of the A record.

Access log— A file where a web server records every HTTP request it receives, including the client IP, request path, status code, and response size. Nginx writes access logs to /var/log/nginx/access.log by default.

ACME protocol— Automatic Certificate Management Environment. The protocol Certbot uses to obtain and renew SSL certificates from Let's Encrypt.

AllowOverride— An Apache HTTP Server directive that controls which directives are permitted in .htaccess files. Setting AllowOverride None disables .htaccess processing entirely.

Authoritative nameserver— A DNS server that holds the original zone records for a domain. Queries to an authoritative nameserver return definitive answers rather than cached copies.

B

BeautifulSoup (bs4)— A Python library for parsing HTML and XML documents. BeautifulSoup extracts data from web pages using methods like find(), find_all(), and CSS selectors. See the BeautifulSoup article.

C

CNAME record— A DNS record type that maps one domain name (an alias) to another domain name (the canonical name). CNAME records cannot coexist with other record types on the same name.

CORS— Cross-Origin Resource Sharing. A browser security mechanism that controls which external domains can access resources on a web server. CORS uses HTTP headers like Access-Control-Allow-Origin to grant or deny cross-origin requests. See the CORS article.

Crawl budget— The number of pages a search engine bot will crawl on a site during a given time period. The robots.txt file influences crawl budget by blocking URLs the bot does not need to visit.

cron— A Linux time-based job scheduler that runs commands at specified intervals. Logrotate relies on cron to trigger log rotation. Cron jobs are defined in crontab files.

D

Delta transfer— A file transfer technique where only the changed portions of a file are sent rather than the entire file. Rsync uses delta transfer with rolling checksums to minimize bandwidth usage.

DHCP— Dynamic Host Configuration Protocol. A network protocol that automatically assigns IP addresses, subnet masks, default gateways, and DNS server addresses to devices on a network. The ipconfig /renew command requests a new DHCP lease.

dig— Domain Information Groper. A command-line DNS query tool that sends queries to DNS servers and displays detailed responses including TTL, authority flags, and query timing. See the dig article.

DNS— Domain Name System. A hierarchical naming system that translates human-readable domain names (e.g., example.com) into IP addresses (e.g., 93.184.216.34).

Document root— The directory from which a web server serves files. Nginx uses root /var/www/html; by default. XAMPP uses the htdocs directory.

E

Error log— A file where a web server records errors, warnings, and diagnostic messages. Nginx writes error logs to /var/log/nginx/error.log by default.

F

FastCGI— A protocol for interfacing web servers with application servers. Nginx uses fastcgi_pass to forward PHP requests to PHP-FPM through the FastCGI protocol.

Firewall— Software or hardware that controls incoming and outgoing network traffic based on security rules. UFW (Uncomplicated Firewall) is the default firewall manager on Ubuntu.

G

Gateway— A network node that connects two different networks. The default gateway is the router that forwards traffic from a local network to the internet. The ipconfig command displays the default gateway address.

H

.htaccess— A per-directory configuration file for Apache HTTP Server. The .htaccess file allows URL rewriting, access control, and authentication without modifying the main server configuration. See the Apache .htaccess article.

htdocs— The default document root directory in XAMPP where Apache serves files from. Located at C:\xampp\htdocs\ on Windows.

HTTP status codes— Three-digit codes returned by web servers to indicate the result of an HTTP request. Common codes: 200 (OK), 301 (redirect), 403 (forbidden), 404 (not found), 500 (internal server error), 502 (bad gateway).

I

ICMP— Internet Control Message Protocol. A network protocol used by traceroute and ping to send diagnostic messages. Traceroute uses ICMP Time Exceeded messages to discover each hop along a network path.

ipconfig— A Windows command-line tool that displays TCP/IP network configuration and manages DHCP leases and DNS cache. See the ipconfig article.

L

Let's Encrypt— A free, automated certificate authority that issues Domain Validation (DV) SSL certificates. Let's Encrypt certificates expire after 90 days and are renewed automatically by Certbot.

Location block— An Nginx configuration block that defines how the server handles requests matching a specific URL path. Location blocks are nested inside server blocks.

Logrotate— A Linux utility that compresses, rotates, and deletes old log files on a schedule. Logrotate runs as a daily cron job and processes files according to rules in /etc/logrotate.d/. See the Logrotate article.

M

MariaDB— A MySQL-compatible relational database server. XAMPP bundles MariaDB as its database component, though the XAMPP Control Panel labels it as "MySQL."

mod_rewrite— An Apache HTTP Server module that enables URL rewriting using regular expressions. mod_rewrite rules are commonly placed in .htaccess files using RewriteRule and RewriteCond directives.

MX record— A DNS record type that specifies the mail server responsible for accepting email for a domain. MX records include a priority value — lower numbers indicate higher priority.

N

Nginx— A high-performance web server and reverse proxy that uses an event-driven architecture. Nginx processes thousands of concurrent connections efficiently. See the Nginx article.

nginx.conf— The primary configuration file for the Nginx web server, located at /etc/nginx/nginx.conf. The file uses a hierarchical block structure: main, events, http, server, and location contexts.

NS record— A DNS record type that identifies the authoritative nameservers for a domain.

nslookup— A command-line tool for querying DNS servers. nslookup supports both interactive and non-interactive modes. See the nslookup article.

P

PHP-FPM— PHP FastCGI Process Manager. A PHP implementation that manages pools of worker processes to handle FastCGI requests from web servers like Nginx.

phpMyAdmin— A web-based interface for managing MySQL and MariaDB databases. phpMyAdmin provides tools for creating databases, running SQL queries, and importing or exporting data. See the phpMyAdmin article.

Preflight request— An HTTP OPTIONS request that browsers send before making certain cross-origin requests. The preflight request checks whether the server allows the actual request's method, headers, and origin. CORS preflight responses can be cached using the Access-Control-Max-Age header.

proxy_pass— An Nginx directive that forwards requests to an upstream server (backend application). Nginx acts as a reverse proxy when using proxy_pass.

PTR record— A DNS record type used for reverse DNS lookups. PTR records map IP addresses back to domain names. The dig -x command queries PTR records.

R

Reverse proxy— A server that sits in front of backend application servers and forwards client requests to them. Nginx functions as a reverse proxy when using proxy_pass or fastcgi_pass directives.

robots.txt— A text file at the root of a website that instructs search engine crawlers which URLs they may or may not access. robots.txt follows the Robots Exclusion Protocol (RFC 9309). See the robots.txt article.

Rsync— A file synchronization utility that transfers and syncs files between local and remote systems using delta transfer. Rsync sends only changed bytes, which reduces bandwidth usage. See the Rsync article.

RTT— Round-Trip Time. The time it takes for a network packet to travel from source to destination and back. Traceroute displays RTT values for each hop along the network path.

S

Server block— An Nginx configuration block that defines how the server handles requests for a specific domain or IP address. Server blocks are similar to Apache virtual hosts.

SSL/TLS— Secure Sockets Layer / Transport Layer Security. Cryptographic protocols that encrypt HTTP traffic between browsers and servers. TLS is the successor to SSL. HTTPS uses TLS to encrypt connections.

T

Traceroute— A network diagnostic tool that maps the path packets take between your machine and a destination. Traceroute uses incrementally increasing TTL values to discover each hop. See the traceroute article.

TTL— Time to Live. In DNS, TTL is the number of seconds a DNS record can be cached before the resolver must query the authoritative server again. In networking, TTL is the maximum number of hops a packet can traverse before being discarded.

U

Upstream server— A backend application server that receives forwarded requests from a reverse proxy. In Nginx, upstream servers are defined with the upstream directive or referenced directly in proxy_pass.

V

Virtual host— A web server configuration that allows multiple domains to be served from a single server. Apache uses <VirtualHost> blocks. Nginx uses server blocks.

X

XAMPP— A cross-platform package that bundles Apache HTTP Server, MariaDB, PHP, and Perl into a single installer for local development. See the XAMPP article.