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Exam 200-301 All Questions

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Exam 200-301 topic 1 question 115 discussion

Actual exam question from Cisco's 200-301
Question #: 115
Topic #: 1
[All 200-301 Questions]

A network engineer must implement an IPv6 configuration on the vlan 2000 interface to create a routable locally-unique unicast address that is blocked from being advertised to the internet. Which configuration must the engineer apply?

  • A. interface vlan 2000 ipv6 address ff00:0000:aaaa::1234:2343/64
  • B. interface vlan 2000 ipv6 address fd00::1234:2343/64
  • C. interface vlan 2000 ipv6 address fe80:0000:aaaa::1234:2343/64
  • D. interface vlan 2000 ipv6 address fc00:0000:aaaa::a15d:1234:2343:8aca/64
Show Suggested Answer Hide Answer
Suggested Answer: B 🗳️

Comments

Chosen Answer:
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cyborg7
Highly Voted 2 years, 2 months ago
D is incorrect as it contains :: which replaced with 0000.0000 will make the address longer than 128bits Correct is B
upvoted 20 times
Frasema
1 year, 1 month ago
You can shorten the '0000' by :: It's not must to have '0000:0000' to use ::
upvoted 6 times
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Sacuxipo
1 year, 10 months ago
fc00 : 0000 : aaaa :: a15d : 1234 : 2343 : 8aca 1st 2nd 3rd 5th 6th 7th 8th I separated in this way to show you that it´is missing the 4th hextet. Guess where it must be? D is correct man.
upvoted 4 times
CCNA_Bro
1 day, 8 hours ago
I would disagree that D is correct. Looking at the address, if, :: is considered has been shortened already, therefore, bringing it back to its normal addressing it would have 9 octets instead of 8.
upvoted 1 times
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FALARASTA
1 year, 8 months ago
You should refer the use of :: it means a a whole hextet but all are zeros
upvoted 1 times
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Dutch012
1 year, 10 months ago
if there is one all-0 quartet, don't use '::', just put one 0 instead. so the correct one is B.
upvoted 2 times
[Removed]
1 year, 8 months ago
RFC4291 recommended that " The use of "::" indicates one or more groups of 16 bits of zeros." refer to https://www.rfc-editor.org/rfc/rfc4291.html
upvoted 3 times
Madzonga
1 year, 3 months ago
it should also be the leftmost if there are two sets of 0s of equal length and in this address there's a group of 16 bits of zeros to the left of ::
upvoted 1 times
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Bl1024
Highly Voted 2 years, 1 month ago
Selected Answer: B
D is wrong address is too long
upvoted 10 times
exiledwl
3 months ago
You're wrong "::" can indeed be used to abbreviate a single set of zeroes (0000)
upvoted 1 times
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chrys
Most Recent 2 months, 3 weeks ago
B is correct. While D falls within the block, that subnet is not currently used. Keep in mind that weird thing about Unique Local addresses: The address block FC00::/7 is actually split into two equally sized halves, fc00::/8 and fd00::/8.fc00::/8, is currently not defined, so while it falls under the Unique Local prefix, it's actually not in use. Currently, only fd00::/8 is used and considered legitimate to assign to an interface.
upvoted 2 times
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exiledwl
3 months ago
Selected Answer: D
Y'all forgetting a key characteristic about ipv6 unique local address which is super relavant here: the 40 bits following "fc" or "fd" MUST be RANDOMLY GENERATED so B is incorrect D is correct and yes :: can be used to abbreviate a single set of "0000"
upvoted 1 times
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cybercerberes
5 months, 4 weeks ago
Selected Answer: B
Nothing other's
upvoted 1 times
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leooooo
6 months, 1 week ago
I just tested on lab. It seems that the address fc00 : 0000 : aaaa :: a15d : 1234 : 2343 : 8aca is legitimate and the command "do show int" shows the interface use the ip without any error . I vote for D.
upvoted 1 times
leooooo
6 months, 1 week ago
I just run answer B to the same interface and command "show ipv6 interface brief" shows the two address. I changed my mind. I will choose answer B because B seems to be a more formal answer according to the discussion.
upvoted 1 times
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emredemircio
6 months, 2 weeks ago
what the... it is surely B
upvoted 1 times
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sabsyed
7 months, 2 weeks ago
d is correct
upvoted 1 times
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BTK0311
7 months, 2 weeks ago
Options A, C, and D do not provide a ULA address. Option D includes an address from the Unique Local Address (ULA) range but also includes a global routing prefix (fc00::/7), which is not typically used for ULAs and may lead to confusion or potential routing issues. Therefore, option B is the correct choice for creating a routable locally-unique unicast address that is not advertised to the Internet.
upvoted 1 times
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9c9566b
8 months ago
Selected Answer: D
To create a locally-unique unicast IPv6 address that is not routable on the internet, the engineer should use a Unique Local Address (ULA), which falls within the fc00::/7 prefix. Therefore, option D is the correct choice: D. interface vlan 2000 ipv6 address fc00:0000:aaaa::a15d:1234:2343:8aca/64
upvoted 1 times
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lmmujsi
8 months, 2 weeks ago
Diretly from CISCO book: NOTE Just to be completely exact, 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
upvoted 6 times
xtraMiles
5 months ago
Agree and upvoting. Per RFC 4193 Section 3.1, "...[zero] my be defined in the future," and Section 3.2.2; Line Item 6 regarding setting the "L" bit to 1, hence the FD. Though the prefix starts w/ FC, application is done using FD.
upvoted 1 times
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[Removed]
9 months ago
Selected Answer: B
B. interface vlan 2000 ipv6 address fd00::1234:2343/64 is correct
upvoted 1 times
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squagmire
9 months, 3 weeks ago
Selected Answer: D
D is correct, the '::' == 0000. that makes it 16 bytes which is 128bits furthermore, it can only be unique-local because it has to be routable within the network(like private ipv4 addresses). one more thing, fc00::/7 is the only one that would be correct as well, cuz thats the start of a unique-local address
upvoted 1 times
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rasadebayor
11 months, 4 weeks ago
The answer to this question is D Here's why: ff00::: These addresses are reserved for multicast purposes and cannot be used for unicast routing. So, option A is incorrect. fd00::: These addresses are unique local addresses (ULA) but are globally routable. So, option B is incorrect. fe80::: These addresses are link-local addresses and cannot be routed outside the local link. So, option C is incorrect. fc00::: These addresses are unique local addresses (ULA) with a globally unique interface identifier (GUID). They are not advertised to the internet by default due to the privacy extension mechanism, while still being routable within the local network. This matches the requirements of the scenario.
upvoted 4 times
Nmk173
11 months, 1 week ago
Hello. Can you give me any source that says fd00:: is globally routable. I think it can not be globally routable.
upvoted 5 times
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PaddyInNZ
12 months ago
Option 'b' is correct. Wow - a lot of confusion here! Options 'b' and 'd' are technically correct - it has nothing to do with IPv6 address length. It's just a matter of which one is "more correct"? ULA is defined as FC00::/7, *however* FC00::/8 is not defined, only FD00::/8 is. For this reason, the answer is 'b'.
upvoted 4 times
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Cyber15
1 year, 1 month ago
Selected Answer: B
B. interface vlan 2000 ipv6 address fd00::1234:2343/64 Explanation: fd00::/8: This is the Unique Local Address (ULA) prefix. It is reserved for local use and is not routable on the public Internet. ULAs are suitable for creating private IPv6 addresses within an organization.
upvoted 3 times
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AbdullahMohammad251
1 year, 1 month ago
I think the correct answer is B because in option D we didn't omit the preceding zeros of the 2nd octet, the ipv6 address should be written as fc00:0:aaaa::a15d:1234:2343:8aca/64
upvoted 3 times
AbdullahMohammad251
1 year, 1 month ago
Also, the double colon is used to represent two or more octets of continuous zeros, this will make our IP address consisting of more than 128 bits
upvoted 4 times
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Community vote distribution
A (35%)
C (25%)
B (20%)
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