Correct answer: B
IANA actually reserves prefix FC00::/7, and not
FD00::/8, for these addresses. FC00::/7 includes all addresses that begin with hex FC
IPv6 Unique local address are in the block of FC00::/7
So , the pattern is composed of the bits that don´t change
F - 1111
C - 1100
/7 - 1111110 Letter B
Letter D is
11111101 - FD , not a Unique Local Address
SOURCE: CCNA 200-301 Official Cert Guide Library - Volume1 page 551
>
"IANA actually reserves prefix FC00::/7, and not FD00::/8, for these addresses. FC00::/7 includes all addresses that begin with hex FC and FD. However, an RFC (4193) requires the eighth bit of these addresses to be set to 1, which means that in practice today, the unique local addresses all begin with their first two digits as FD"
Therefore, option D 11111101 (Hex FD) is the only correct answer
AI said: Thank you for providing the search results. Based on the majority of search results, the correct answer to this question is B. 11111100, as it refers to the first 7 bits of an IPv6 Unique Local Address which have an exact binary pattern of 1111 1100
The 8th bit of a Unique Local Address (ULA) in IPv6 is always set to "1", which is often referred to as the "L" (Local) bit, indicating that the address is locally assigned and not routable on the public internet; this translates to the hexadecimal value "D" in the prefix "fd00::/8" where the first 8 bits are "11111101"
Option D is Correct: According to RFC 4193 section 3.2.2, the 8th bit of a Unique Local Address should be set to 1. Therefore, there is no room for other discussions since RFC clearly stated that.
No, the correct answer is indeed B. 11111100.
This prefix (11111100 in binary) corresponds to fc00::/7, which is reserved for IPv6 Unique Local Addresses (ULAs). ULAs are designated for use in private networks and are not meant to be routable on the public internet. The prefix 11111101 (option D) is not used for ULAs and does not correspond to any specific IPv6 address type.
Another poorly designed Cisco question. IANA reserved FC00::/7 range but RFC4193 requires FD00::/8. In reality all unique local addresses are FD00::/8. The question does not give the context. Both B and D are possible.
Since network knowledge is intended to be applied in actual work, I'd choose D, which is more useful and correct in reality.
The correct binary pattern for a unique IPv6 unique local address is:
D. 11111101
Unique local addresses (ULAs) in IPv6 are in the address block fc00::/7. The first 7 bits of the address are fixed as 1111110. However, for locally assigned addresses (as opposed to centrally assigned), the next bit is 1, making the first 8 bits 11111101.
At first, I picked B. But, according to wikipedia, "unique local addresses use prefix fc00::/7. The first bit (8th position) following the prefix (/7 notation) indicates, if set, that the address is locally assigned. This splits the address block in two equally sized halves, fc00::/8 and fd00::/8."
What we currently use though is the fd00::/8 block.
Also from wiki, "the block with L = 0, fc00::/8, is currently not defined.[1] It has been proposed that an allocation authority manage it, but this has not gained acceptance in the IETF [...]."
Also, as per RFC 4193 (October 2005), Par. 3.2.2, Line Item 6, the 8th bit (also called "L" bit) is "concatenated" (joined) w/ FC00::/7 with L bit set to 1, making it FD00. Hence, the binary 1111 1101 which, btw, is what I'm choosing .
FC00::/7 is d reserved space for ULA BUT the 8th bit of that address space used for ULA must be 1 ( which is FD00::/8 which in bits means 11111101) while the address space of FC00::/7 whose 8th bit is 0 is reserved for future purposes (which is FC00::/8 which in bits means is 11111100). Don’t confuse FC00::/7 with FC00::/8.
FC00::/7 means 1111110 (first 7 bits) is d network part and fixed while the 8th bit is part of the host address while FC00::/8 means 11111100 (the full FC00 which is 8 bits) is the network address and the fixed part.
The main part that is ULA in FC00::/7 is the 11111101 part which is the FD00::/8. So the right answer is D. If B was 1111110, then it would have been correct too.
The binary pattern of a Unique Local Address (ULA) in IPv6 is determined by the prefix assigned to it. The prefix for Unique Local Addresses is fd00::/8.
To represent the binary pattern of this prefix, we convert each hexadecimal digit to its corresponding 4-bit binary representation. In this case, the prefix fd would be represented as 11111101 in binary.
Therefore, the correct answer is D: 11111101.
IPv6 Unique Local Addresses (ULAs) have a binary pattern of 11111100 at the start of the address. This corresponds to fc00::/7 in IPv6 notation. However, it’s worth noting that according to the standards defined by the Internet Engineering Task Force (IETF), only addresses from the fd00::/8 block (binary pattern 11111101) should be used for ULAs. This leaves the fc00::/8 block (binary pattern 11111100) reserved for future use.
it´s B
fc00::/8 (1111 1100): When the L flag is set to 0, may be defined in the future.
fd00::/8 (1111 1101): When the L flag is set to 1, the address is locally assigned.
The last bit is called the L bit.
L=0 is not defined yet
L=1 is locally specified
the question is about "ipv6 unique local" so it´s FC00::/7 or 11111100
if the question was "locally specified ipv6 unique local" then we must answer FD00::/8 or 11111101
it´s B
fc00::/7 (1111 1100): When the L flag is set to 0, may be defined in the future.
fd00::/8 (1111 1101): When the L flag is set to 1, the address is locally assigned.
The last bit is called the L bit.
L=0 is not defined yet
L=1 is locally specified
the question is about "ipv6 unique local" so it´s FC00::/7 or 11111100
if the question was "locally specified ipv6 unique local" then we must answer FD00::/8 or 11111101
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