How to Abbreviate a IPv6 Address?

Daniel Loyer

Hi Ronnie:

I found this CCENT/CCNA Either Todd Lammle or Wendell Book? Inside the book it has Practice questions, I came across this question, but I can't find the answers to these questions?

Questions: This is a IPv6 Address (full Length) but it needs to be abbreviated? or in short form?

Question 1) 2340:0000:0010:0100:1000:ABCD:0101:1010

My answer is this 2340::(Trunkcate)10:100(Omit leading zeros):1000: ABCD:101:A

2340::10:100:1000:ABCD:101:A ? would this be correct?

Dan L.

Ronnie Wong

@Daniel-Loyer said in How to Abbreviate a IPv6 Address?:

Hi Ronnie:

I found this CCENT/CCNA Either Todd Lammle or Wendell Book? Inside the book it has Practice questions, I came across this question, but I can't find the answers to these questions?

Questions: This is a IPv6 Address (full Length) but it needs to be abbreviated? or in short form?

Question 1) 2340:0000:0010:0100:1000:ABCD:0101:1010

My answer is this 2340::(Trunkcate)10:100(Omit leading zeros):1000: ABCD:101:A

2340::10:100:1000:ABCD:101:A ? would this be correct?

Dan L.

OK... so here's the answer from the router:

R1(config-if)#ipv6 address 2340:0000:0010:0100:1000:ABCD:0101:1010/64
R1(config-if)#do show ipv6 interface brief
FastEthernet0/0        [administratively down/down]
    unassigned
FastEthernet0/1        [administratively down/down]
    FE80::C801:3AFF:FEDF:6
    2340:0:10:100:1000:ABCD:101:1010

To verify...I went to https://www.ultratools.com/tools/ipv6Compress
entered 2340:0000:0010:0100:1000:ABCD:0101:1010
output: 2340:0:10:100:1000:abcd:101:1010

I'm kinda stumped why this didn't truncate the to :: but instead:0:
If I find anything else...or if someone else knows they may answer here.

PS Since this is actually only reducing within a single hextet, I believe it's not meeting some rule for the :: truncation...so they instead reduce the space to a single 0.
when there are multiple "hextet" involved it truncates fine:

R1(config-if)#ipv6 address 2001:0000:0000:1000:1000:ABCD:101:1010/64
R1(config-if)#do show ipv6 interface brief
FastEthernet0/0        [administratively down/down]
    FE80::C801:3AFF:FEDF:8
    2001::1000:1000:ABCD:101:1010
FastEthernet0/1        [administratively down/down]
    FE80::C801:3AFF:FEDF:6
    2340:0:10:100:1000:ABCD:101:1010