In Internet Protocol version 6 (IPv6), how long is an IP address in terms of bits and what does this length provide compared with IPv4?

Introduction / Context:
IPv4, the older version of the Internet Protocol, uses 32 bit addresses, which limits the total number of unique IP addresses. To support the growth of the internet and connected devices, IPv6 was introduced with longer addresses. This question asks you to recall the length of an IPv6 address and understand its significance.

Given Data / Assumptions:

• IPv4 addresses are 32 bits long.
• IPv6 was designed to provide many more addresses.
• We are comparing bits and bytes, so careful unit reading is important.

Concept / Approach:
An IPv6 address is 128 bits long. Since each bit can be zero or one, the total number of possible addresses is 2 raised to the power 128, which is an extremely large number compared with 2 raised to the power 32 for IPv4. This enormous address space allows for better address allocation, new addressing schemes, and room for future growth. IPv6 addresses are usually written as eight groups of four hexadecimal digits separated by colons, reflecting the 128 bit length.

Step-by-Step Solution:
Step 1: Recall that IPv4 uses 32 bit addresses like 192.168.1.1, which limits the number of unique addresses.Step 2: IPv6 was specifically designed to expand this space, and its addresses are 128 bits long.Step 3: Distinguish between bits and bytes. 128 bits is 16 bytes, not 128 bytes.Step 4: Recognize that an address of 128 bytes would be excessively large for routing tables and packet headers.Step 5: Select the option that correctly states 128 bits and mentions the larger address space.

Verification / Alternative check:
Look at an example IPv6 address such as 2001:0db8:85a3:0000:0000:8a2e:0370:7334. Each hexadecimal digit represents four bits, there are 32 hex digits total, so 32 multiplied by 4 gives 128 bits. This confirms the bit length and matches the standard definition of IPv6 addressing.

Why Other Options Are Wrong:
Option B: Claims IPv6 uses 32 bits, which would not solve the address exhaustion problem and contradicts official standards.Option C: States 128 bytes, which is eight times larger than 128 bits and not used for IP addresses.Option D: Suggests 32 bytes, which is 256 bits and does not match the actual IPv6 specification.

Common Pitfalls:
Some learners confuse bits and bytes, especially when converting between hexadecimal notation and binary length. Another pitfall is remembering that IPv6 is larger than IPv4 but not recalling the exact number of bits. Keeping the number 128 in mind as four times 32 can help associate IPv6 with a four times longer address field.

Final Answer:
The correct answer is An IPv6 address is 128 bits long, providing a vastly larger address space than IPv4.