Quiz: Nginx & Web Servers

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4 questions

L0 (1 questions)

1. Why must you always run 'nginx -t' before 'nginx -s reload'?

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nginx -t tests the configuration syntax without applying it. If the config has errors and you reload without testing, Nginx may fail to reload and in some cases the workers can crash, causing downtime. Testing first is a zero-cost safety check that prevents config errors from reaching production.

L1 (1 questions)

1. Explain the proxy_pass trailing slash behavior: what is the difference between 'proxy_pass http://backend' and 'proxy_pass http://backend/'?

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Without trailing slash: the location path is appended to the backend URL. Request to /app/page proxies to backend/app/page. With trailing slash: the location path is replaced. Request to /app/page (in a 'location /app/' block) proxies to backend/page. This is a top-5 Nginx misconfiguration — getting it wrong sends mangled paths to the backend.

L2 (1 questions)

1. Describe the Nginx location matching priority order. If you have 'location /api' and 'location ~ /api', which wins?

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Priority order:
1. Exact match (=) — highest.
2. Prefix with ^~ — stops regex evaluation.
3. Regex (~ or ~*) — first match in config order wins.
4. Plain prefix — longest match, lowest priority. So 'location ~ /api' (regex) beats 'location /api' (plain prefix) because regex is evaluated after prefix matching and takes precedence unless the prefix uses ^~.

L3 (1 questions)

1. How do you configure Nginx upstream health checks and keepalive connections for a backend pool?

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Define an upstream block with servers using max_fails=3 and fail_timeout=30s for passive health checks. Add 'keepalive 32' for persistent backend connections. In the location block, set proxy_http_version 1.1 and proxy_set_header Connection '' (empty string, required for keepalive). Choose a load balancing method: least_conn for uneven request costs, ip_hash for sticky sessions.