Networking fundamentals: IPv4 addresses use how many bits for the full address length?

Introduction / Context:
Internet Protocol version 4 (IPv4) is the classic addressing scheme still widely used across the Internet. Knowing the bit length of IPv4 addresses is a foundational networking concept and explains address exhaustion issues.

Given Data / Assumptions:

• The question refers specifically to IPv4 (not IPv6).
• IPv4 addresses are commonly written in dotted-decimal notation with four octets.
• Each octet represents 8 bits.

Concept / Approach:
IPv4 uses 32 bits in total. The dotted-decimal format (a.b.c.d) corresponds to four 8-bit octets, totaling 32 bits. This supports approximately 4.29 billion unique addresses before factoring in reservations and subnetting.

Step-by-Step Solution:

Verification / Alternative check:
Observe subnet masks such as 255.255.255.0 which correspond to 24 network bits; CIDR notation /x signifies the number of bits, confirming a 32-bit ceiling (e.g., /32 for a host route).

Why Other Options Are Wrong:
16-bit, 8-bit: Too small for IPv4 and do not match dotted-decimal structure. 64-bit: Refers to IPv6 fragments (IPv6 is 128-bit), not IPv4. None of the above: Incorrect because 32-bit is correct.

Common Pitfalls:
Confusing IPv4 with IPv6; mixing IPv4 CIDR prefix lengths with total address size; assuming dotted notation implies decimal rather than binary-based octets.

Final Answer:
32-bit addresses