The abbreviation of IPv6 addresses follows two main rules as defined in RFC 5952:

1. Zero Compression: The longest contiguous sequence of 16-bit zero-value hextets is replaced by a double colon (::). This can only be done once. If there are multiple blocks of zeros of the same longest length, the first one is compressed.

2. Leading Zero Omission: Leading zeros within any 16-bit hextet can be removed.

Applying these rules to BFEA:DACA:0000:0000:9390:0000:0000:D91:

1. There are two blocks of consecutive zeros (0000:0000), both of equal length. The rule dictates compressing the first block. This yields BFEA:DACA::9390:0000:0000:D91.

2. Next, leading zeros in the remaining hextets are omitted. The 0000 fields become 0. This results in the final abbreviated address: BFEA:DACA::9390:0:0:D91.

A. BFEA:DACA::9390::D91 is incorrect because the double colon (::) can only be used once in an address to avoid ambiguity.

B. BFEA:DACA::9390:0:D91 is incorrect as it expands to BFEA:DACA:0000:0000:0000:9390:0000:D91, which is not the original address.

C. BFEA:DACA::D91/6 is incorrect. The /6 notation indicates a network prefix length, not part of the host address abbreviation.

1. Hinden

R.

& Deering

S. (2006). IP Version 6 Addressing Architecture. RFC 4291

Section 2.2. IETF.

This document outlines the fundamental rules for representing IPv6 addresses

including the use of "::" to compress zeros and the omission of leading zeros in a field.

2. Kawamura

S.

& Kawashima

M. (2010). A Recommendation for IPv6 Address Text Representation. RFC 5952

Section 4.2.3. IETF.

This RFC provides the canonical representation rules. Section 4.2.3 explicitly states: "If the length of the runs of zero bits are equal

the first run of zero bits MUST be shortened." This directly supports the choice of compressing the first 0000:0000 block.

3. Stanford University. (2021). CS144: Introduction to Computer Networking

Lecture 10: The Internet Protocol. Courseware.

Lecture slides and notes for this course typically cover IPv6 addressing

explaining the two main rules for abbreviation: compressing the longest string of zeros with :: (only once) and dropping leading zeros from each hextet. This aligns with the logic used to derive the correct answer.