Wildcard and regex server names in Nginx - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to define a server block that listens to all subdomains of example.com.

Nginx

server {
    server_name [1];
    listen 80;
}

Drag options to blanks, or click blank then click option'

A*.example.com

Bexample.*

Cexample.com

Dwww.example.com

Attempts:

3 left

💡 Hint

Common Mistakes

Using the wildcard at the end like example.* does not work.

Using the exact domain name does not match subdomains.

The wildcard *.example.com matches all subdomains of example.com, like app.example.com or blog.example.com.

2fill in blank

medium

Complete the code to define a server block that matches any domain ending with .test.

Nginx

server {
    server_name ~[1];
    listen 80;
}

Drag options to blanks, or click blank then click option'

A\\.test

B^test\\.

Ctest$

D\\.test$

Attempts:

3 left

💡 Hint

Common Mistakes

Not escaping the dot causes it to match any character.

Placing the caret (^) at the start matches beginning, not end.

The regex \.test$ matches any domain ending with .test. The backslash escapes the dot, and $ means end of string.

3fill in blank

hard

Fix the error in the regex server_name to match domains starting with 'app' followed by any characters.

Nginx

server {
    server_name ~[1];
    listen 80;
}

Drag options to blanks, or click blank then click option'

Aapp.*$

B^app.*$

C^app$

Dapp^.*$

Attempts:

3 left

💡 Hint

Common Mistakes

Missing the caret causes the regex to match 'app' anywhere, not just at start.

Placing caret in the middle is invalid.

The regex ^app.*$ matches any domain starting with 'app' followed by any characters. The caret ^ marks the start, and .* means any characters.

4fill in blank

hard

Fill both blanks to create a server block matching domains starting with 'dev' or 'test' followed by '.example.com'.

Nginx

server {
    server_name ~^([1]|[2])\.example\.com$;
    listen 80;
}

Drag options to blanks, or click blank then click option'

Adev

Bprod

Ctest

Dstage

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong domain prefixes like 'prod' or 'stage'.

Not escaping dots causes wrong matches.

The regex ^(dev|test)\.example\.com$ matches domains starting with 'dev' or 'test' followed by '.example.com'.

5fill in blank

hard

Fill all three blanks to create a server block matching any subdomain of 'example.com' except 'www'.

Nginx

server {
    server_name ~^(?![1])[2]\.example\.[3]$;
    listen 80;
}

Drag options to blanks, or click blank then click option'

Awww

B[a-z0-9-]+

Ccom

Dnet

Attempts:

3 left

💡 Hint

Common Mistakes

Not using negative lookahead causes 'www' to match.

Using wrong top-level domain like 'net' instead of 'com'.

The regex uses a negative lookahead (?!www) to exclude 'www', then matches any subdomain with [a-z0-9-]+, and ends with '.example.com'.

Practice

1. What does a wildcard server name like *.example.com match in nginx?

easy

A. Any domain ending with example.com, including example.com itself

B. Only the exact domain example.com

C. Any subdomain of example.com, like blog.example.com or shop.example.com

D. Only domains starting with a star character

Solution

1. Step 1: Understand wildcard usage in server names

   A wildcard * before a domain matches any subdomain part, but not the root domain itself.

2. Step 2: Apply to *.example.com

   This matches domains like blog.example.com or shop.example.com, but not example.com alone.

3. Final Answer:

   Any subdomain of example.com, like blog.example.com or shop.example.com -> Option C

4. Quick Check:

   Wildcard * matches subdomains only [OK]

Hint: Wildcard * matches subdomains, not the root domain [OK]

Common Mistakes:

• Thinking wildcard matches the root domain
• Confusing wildcard with regex syntax
• Assuming wildcard matches any domain ending

2. Which of the following is the correct syntax to define a regex server name in nginx?

easy

A. server_name /www\d+\.example\.com/;

B. server_name *example.com;

C. server_name ^www\d+\.example\.com$;

D. server_name ~^www\d+\.example\.com$;

Solution

1. Step 1: Recall regex server name syntax in nginx

   Regex server names start with a tilde ~ followed by the regex pattern.

2. Step 2: Check each option

   server_name ~^www\d+\.example\.com$; uses ~^www\d+\.example\.com$ which is correct regex syntax. Others either miss the tilde or use invalid delimiters.

3. Final Answer:

   server_name ~^www\d+\.example\.com$; -> Option D

4. Quick Check:

   Regex server names start with ~ [OK]

Hint: Regex server names always start with ~ in nginx [OK]

Common Mistakes:

• Omitting the ~ before regex pattern
• Using * instead of ~ for regex
• Using slashes / / as regex delimiters

3. Given this nginx config snippet:

server {
  server_name ~^www\d+\.example\.com$;
  return 200 'Matched regex server name';
}

What will be the response for a request to www12.example.com?

medium

A. Matched regex server name

B. 500 Internal Server Error

C. 404 Not Found

D. Default nginx welcome page

Solution

1. Step 1: Understand the regex pattern

   The regex ^www\d+\.example\.com$ matches domains starting with 'www' followed by one or more digits, then '.example.com'.

2. Step 2: Check if 'www12.example.com' matches

   'www12.example.com' matches the pattern because '12' are digits after 'www'.

3. Final Answer:

   Matched regex server name -> Option A

4. Quick Check:

   Regex matches www12.example.com [OK]

Hint: Check if domain fits regex pattern exactly [OK]

Common Mistakes:

• Assuming regex matches partial strings
• Ignoring start ^ and end $ anchors
• Confusing regex with wildcard matching

4. You wrote this nginx config:

server {
  server_name ~www\d+\.example\.com$;
  return 200 'Hello';
}

Why is this regex server_name directive incorrect?

medium

A. Missing ^ anchor at start of regex

B. Regex server name must start with ~ and pattern must start with ^

C. Regex pattern missing delimiters like / /

D. Regex server name must start with ~ and pattern must be valid

Solution

1. Step 1: Check regex server_name syntax

   Regex server names must start with ~ and the pattern should start with ^ to match from the beginning.

2. Step 2: Identify missing ^ anchor

   The pattern www\d+\.example\.com$ lacks the ^ anchor, causing partial matches rather than full hostname matches.

3. Final Answer:

   Regex server name must start with ~ and pattern must start with ^ -> Option B

4. Quick Check:

   Regex patterns need ^ anchor at start [OK]

Hint: Regex patterns should start with ^ for nginx server_name [OK]

Common Mistakes:

• Omitting ^ anchor in regex pattern
• Thinking delimiters like / / are needed
• Ignoring nginx error messages about regex

5. You want nginx to serve requests for any subdomain of example.com except www.example.com. Which server_name config achieves this?

hard

A. server_name ~^(?!www\.)[^.]+\.example\.com$;

B. server_name *.example.com www.example.com;

C. server_name ~^www\d+\.example\.com$;

D. server_name example.com *.example.com;

Solution

1. Step 1: Understand the requirement

   We want to match any subdomain except 'www.example.com'. This requires a regex with negative lookahead.

2. Step 2: Analyze options

   server_name ~^(?!www\.)[^.]+\.example\.com$; uses ~^(?!www\.)[^.]+\.example\.com$ which matches any subdomain not starting with 'www.'. Others either include 'www' or don't exclude it.

3. Final Answer:

   server_name ~^(?!www\.)[^.]+\.example\.com$; -> Option A

4. Quick Check:

   Negative lookahead excludes www subdomain [OK]

Hint: Use negative lookahead in regex to exclude specific subdomains [OK]

Common Mistakes:

• Using wildcard that includes www.example.com
• Not using regex for exclusion
• Confusing wildcard and regex syntax