IPv6 confused

Hello,

I need some help cause i dont understand a thing !!!!

Q1. Which option is a valid IPv6 address

A. 2001:0000:130F::099A::12A
B. 2002:7654:A1AD:61:81AF:CCC1
C. FEC0:ABCD:WXYZ:0067::2A4
D. 2004:1:25A4:886F::1

Correct is D.
I can understand why A is not correct (2 ::) but what about the othe 3 ?
B seems to be correct and C is a unique local address (FEC) so why is not correct

Q2. Identify valid IPv6 addresses (choose 4)

A. ::
B. ::192:168:0:1
C. 2000::
D. 2001:3452:4952:2837::
E. 2002:C0A8:101::42
F. 2003:dead:beef:4dad:46db:101

Correct is ABEF why ?????

Q3. Which IPv6 address is valid ?

A. 2031:0:130F::9C0:876A:130B
B. 2001:0db8:0:130H::87c:140B
C. 2001:0db8:0000:130F:0000:0000:086c:140B
D. 2031::130F::9c0:876A:130B

Correct is A.
oK for D but what about B or C it seems to be right

Please give me some help....

Taking the exam at the end of this month and i need to clear things in my mind

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Comments

NetworkVeteran

daras wrote: »

Hello,
Q1. Which option is a valid IPv6 address

A. 2001:0000:130F::099A::12A
B. 2002:7654:A1AD:61:81AF:CCC1
C. FEC0:ABCD:WXYZ:0067::2A4
D. 2004:1:25A4:886F::1
I can understand why A is not correct (2 ::'s)

As you suspect, there's more being tested here than knowing that an IPv6 address can have zero or one ::'s. Items to study that will making solving these simpler: How many colons should be in an IPv6 addres? How many characters may go between colons? What characters may go between colons? What does the address '::' signify? Where in an address is '::' allowed?

That said, the answers to Q2 and Q3 look incorrect.

NetworkVeteran

Here's where I disagree with the exam's author--

Q2--
C. 2000:: (good address)
D. 2001:3452:4952:2837:: (good address)
F. 2003:dead:beef:4dad:46db:101 (bad - this address only has six parts)

Q3--
C. 2001:0db8:0000:130F:0000:0000:086c:140B (good address)

NetworkVeteran

I just double-checked w/ the RFC and a router. I was correct in my disagreement. If this is representative of the test author's questions--and not simply the most confusing you found--I'd look elsewhere for your practice questions.

theodoxa

A. 2001:0000:130F::099A::12A

(INVALID) 2 Sets of Double Colons

B. 2002:7654:A1AD:61:81AF:CCC1

(INVALID) Not Enough Bits. An IPv6 Address is 128 bits divided into 8 whatever you call the IPv6 version of Octets (Hexadecets?) This Address has only 6, not 8.

C. FEC0:ABCD:WXYZ:0067::2A4

(INVALID) Contains Characters other than 0-9, A-F.

D. 2004:1:25A4:886F::1

(VALID) Globally Routable IPv6 Address.

mac2be

theodoxa. Excellent information. Still a beginner learning the ipv6 and your comments really helped us all out! Thanks

TechGuru80

Q1:

You can only do :: one time for groups of zeros, so not A. B is not 8 octets...so that is wrong. C uses XYZ automatically making it wrong. Also C probably meant FE80 not FEC0 (but FEC0 is not even something real).

Q2:

Well you can't have 0's for the host on a real address such as 2000. Same story with D, you cannot end it with 0s.

Q3:

On B, you cannot remove the leading zeros in one section and not in another...look at the 87c part. It could be saying C is wrong because it is not the MOST CORRECT answer...still has leading zeros and groups of zeros.

theodoxa

TechGuru80 wrote: »

but FEC0 is not even something real

FEC0::/10 is/was a "Site-Local" Address. This was a block of IP Addresses (IPv6 Equivalent of RFC 191

that was set aside from 1995 to 2004 for Private IPs. In 2005 it was replaced with FC00::/7 (Now called "Unique-Local"). That said, using characters other than 0-9, A-F makes the address invalid, much like how you'll see IPv4 Addresses on TV with octets greater than 255.

atorven

I never knew that once you remove a leading in an octet, you had to remove other leading zeros from other subsequent octets. Cheers