Root directive in Nginx - Practice Problems & Coding Challenges

Challenge - 5 Problems

💻 Command Output

intermediate

What is the output of accessing the root URL?

Given this nginx server block configuration, what file will nginx serve when a user accesses http://example.com/?

Nginx

server {
    listen 80;
    server_name example.com;
    root /var/www/html;
    index index.html index.htm;
}

A /var/www/html/index.html

B /var/www/index.html

C /var/www/html/default.html

D /var/www/html/home.html

💡 Hint

Check the root and index directives to find the default file served.

The root directive sets the base directory for files. The index directive lists files nginx tries to serve by default. Here, index.html is the first file nginx looks for inside /var/www/html.

❓ Configuration

intermediate

Identify the correct root directive placement

Where should the root directive be placed to serve files correctly for a specific location?

Nginx

server {
    listen 80;
    server_name example.com;

    location /images/ {
        # Where to place root?
    }
}

A Inside the <code>location /images/</code> block

B Only inside the <code>server</code> block, not inside <code>location</code>

C Outside both <code>server</code> and <code>location</code> blocks

D Inside the <code>http</code> block only

💡 Hint

Think about how nginx uses root for different URL paths.

The root directive can be set inside a location block to specify a different root directory for that path. This overrides the server-level root for that location.

❓ Troubleshoot

advanced

Why does nginx return 404 for a valid file?

Given this configuration, nginx returns 404 when accessing http://example.com/images/pic.jpg even though the file exists at /var/www/images/pic.jpg. What is the cause?

Nginx

server {
    listen 80;
    server_name example.com;
    root /var/www/html;

    location /images/ {
        root /var/www/images;
    }
}

A Because the root directive inside location is ignored, so nginx looks in /var/www/html/images/pic.jpg

B Because nginx appends the location URI to the root, resulting in /var/www/images/images/pic.jpg which does not exist

C Because the file permissions on /var/www/images/pic.jpg are incorrect

D Because the server_name does not match the request

💡 Hint

Remember how nginx combines root and the request URI inside location.

When root is used inside a location, nginx appends the full request URI to the root path. So for request URI /images/pic.jpg and root /var/www/images, it constructs /var/www/images/images/pic.jpg. This file does not exist, causing 404.

✅ Best Practice

advanced

Choose the best way to serve static files from a subdirectory

You want to serve static files from /var/www/static when users access /static/ URL. Which configuration is best?

A location /static/ { root /var/www; }

B location /static/ { root /var/www/static; }

C location /static/ { alias /var/www/static/; }

D location /static/ { proxy_pass http://localhost/static/; }

💡 Hint

Consider how root and alias handle URI paths differently.

The alias directive replaces the location part of the URI with the specified path, so alias /var/www/static/; correctly maps /static/file to /var/www/static/file. Using root would duplicate the /static/ part in the path, causing errors.

🧠 Conceptual

expert

How does nginx resolve the root path with nested locations?

Consider this nginx configuration:

server {
    listen 80;
    server_name example.com;
    root /var/www/html;

    location / {
        root /var/www/site;

        location /images/ {
            root /var/www/images_root;
        }
    }
}

What is the full filesystem path nginx will use to serve http://example.com/images/pic.jpg?

A /var/www/html/images/pic.jpg

B /var/www/images_root/pic.jpg

C /var/www/site/images/pic.jpg

D /var/www/images_root/images/pic.jpg

💡 Hint

Remember that nested location blocks override the root directive independently.

The innermost location /images/ block sets root /var/www/images_root;. Nginx appends the full request URI /images/pic.jpg to this root, resulting in /var/www/images_root/images/pic.jpg.