Which of the following is not a valid web address?

Correct option is A

The web address https://www.red&blue.com is not valid because the ampersand symbol (&) is not allowed in domain names. Domain names can contain letters (a–z), digits (0–9), and hyphens (–), but special characters like & are prohibited. The remaining options follow standard URL and domain-naming rules, making them valid web addresses.
Important Key Points:
1. Standard Structure of a Web Address (URL): A URL generally follows the format: protocol://domain-name.
2. Allowed Characters in Domain Names: Letters, numbers, dots (.), and hyphens (–) are permitted.
3. Disallowed Characters: Special symbols such as &, %, @, #, spaces are not allowed in domain names.
4. Role of Protocols: Both http and https are valid web protocols used to access websites.
5. Subdomains: Multiple dots (as in www.red.blue.com) are valid and represent subdomains.
6. Real-World Importance: Invalid characters in a URL prevent proper DNS resolution and website access.
Knowledge Booster:
· Why option (b) is valid? https://www.red.blue.com uses valid subdomains and allowed characters.
· Why option (c) is valid? http://www.red.blue.com is valid; both http and https are acceptable protocols.
· Why option (d) is valid? Hyphens (–) are allowed in domain names, making http://www.red-blue.com valid.