Apache HTTP Server Configuration Cheat Sheet

Updated 2026-03-18

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Apache HTTP Server (httpd) is the world's most widely used open-source web server, powering millions of websites since 1995. It provides a highly configurable, modular architecture that enables administrators to customize server behavior through configuration files (typically httpd.conf and .htaccess), supporting everything from simple static sites to complex multi-domain hosting with SSL encryption, reverse proxying, load balancing, and fine-grained access control. Understanding Apache's directive-based configuration system is essential for securing production environments, optimizing performance under high traffic, troubleshooting request routing issues, and implementing modern features like HTTP/2 and WebSocket proxying—making it a critical skill for DevOps engineers, system administrators, and web developers managing server infrastructure.

What This Cheat Sheet Covers

This topic spans 23 focused tables and 149 indexed concepts. Below is a complete table-by-table outline of this topic, spanning foundational concepts through advanced details.

Table 1: Virtual Host ConfigurationTable 2: Core Server DirectivesTable 3: Directory and Access ControlTable 4: .htaccess ConfigurationTable 5: URL Rewriting (mod_rewrite)Table 6: Reverse Proxy and Load BalancingTable 7: SSL/TLS Configuration (mod_ssl)Table 8: MPM (Multi-Processing Module) ConfigurationTable 9: HTTP Connection ManagementTable 10: Logging ConfigurationTable 11: Performance and CachingTable 12: Compression (mod_deflate)Table 13: Authentication and SecurityTable 14: Security HardeningTable 15: HTTP Headers (mod_headers)Table 16: Environment VariablesTable 17: Redirects and URL ManipulationTable 18: Advanced Proxy FeaturesTable 19: HTTP/2 ConfigurationTable 20: WebSocket Proxy SupportTable 21: CGI and Script ExecutionTable 22: Content NegotiationTable 23: Access Control (legacy Apache 2.2 syntax)

Table 1: Virtual Host Configuration

Directive	Example	Description
VirtualHost	`<code><VirtualHost *:80></code><br>` `ServerName example.com` `</VirtualHost>`	• Defines a named or IP-based virtual host container that isolates configuration for a specific site • matches requests based on IP address and port.
ServerName	`ServerName www.example.com:80`	• Specifies the canonical hostname and port the server uses to identify itself • essential for name-based virtual hosting and generating self-referential URLs.
ServerAlias	`ServerAlias example.com *.example.com`	• Defines alternate names for the virtual host • supports wildcards to match multiple subdomains within a single VirtualHost block.
DocumentRoot	`DocumentRoot "/var/www/html"`	• Sets the root directory from which Apache serves files • must point to an existing directory with appropriate permissions.

Table 1: Virtual Host Configuration

Directive	Example	Description
VirtualHost	`<code><VirtualHost *:80></code><br>` `ServerName example.com` `</VirtualHost>`	• Defines a named or IP-based virtual host container that isolates configuration for a specific site • matches requests based on IP address and port.
ServerName	`ServerName www.example.com:80`	• Specifies the canonical hostname and port the server uses to identify itself • essential for name-based virtual hosting and generating self-referential URLs.
ServerAlias	`ServerAlias example.com *.example.com`	• Defines alternate names for the virtual host • supports wildcards to match multiple subdomains within a single VirtualHost block.
DocumentRoot	`DocumentRoot "/var/www/html"`	• Sets the root directory from which Apache serves files • must point to an existing directory with appropriate permissions.