CompTIA Security+ (SY0-401) — Question 21

While testing a new host based firewall configuration a security administrator inadvertently blocks access to localhost which causes problems with applications running on the host. Which of the following addresses refer to localhost?

Answer options

• A. ::0
• B. 127.0.0.0
• C. 120.0.0.1
• D. 127.0.0/8
• E. 127::0.1

Correct answer: C

Explanation

The correct answer is C, as 120.0.0.1 is not a valid localhost address. The addresses A (::0), B (127.0.0.0), D (127.0.0/8), and E (127::0.1) are all valid representations of localhost, with 127.0.0.1 being the most commonly used address.