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Chapter 6: Web Servers — Nginx and Apache

Interview Questions

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Q1. What is the difference between Nginx and Apache?
Nginx is event-driven and asynchronous, very efficient for static content and reverse proxying. Apache uses process/thread-based MPMs, has many modules and supports per-directory .htaccess files.
Q2. What is a reverse proxy?
A server that receives client requests and forwards them to backend servers/apps (e.g. Node on 127.0.0.1:3000), then returns the response. It provides TLS termination, caching, load balancing and security.
Q3. How do you test Nginx configuration before applying it?
sudo nginx -t, then sudo service nginx reload if the test passes.
Q4. What do HTTP 403, 404 and 502 mean?
403 Forbidden (permission/SELinux/no index), 404 Not Found (wrong path/root), 502 Bad Gateway (the upstream app behind the proxy is down or unreachable).
Q5. What is SELinux and how do you fix a web-content label issue?
Security-Enhanced Linux, a mandatory access control system on RHEL/CentOS. Fix labels with sudo restorecon -Rv /var/www/site (or semanage fcontext for custom paths).
Q6. What is .htaccess and why doesn't Nginx support it?
A per-directory Apache config file read on every request. Nginx avoids it for performance; all configuration lives in central files.