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IPv6 Addresses - Compression

IPv6 addresses can be shortened by removing leading zeros and replacing consecutive all-zero groups with a double colon, which can only be applied once per address. This content covers the rules and hands-on practice for applying both compression techniques correctly.

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About this video

IPv6 addresses follow a specific compression standard that keeps notation concise without introducing ambiguity. Two rules govern this process: leading zeros in any 16-bit hexadecimal group are optional and can be dropped, and a consecutive sequence of all-zero groups can be replaced with a double colon. The double colon substitution is permitted only once per address, because using it more than once would make it impossible to determine how many zero groups were removed from each position. Applying these rules correctly requires careful attention to which zeros are leading zeros within a group and which zeros form complete all-zero groups eligible for double-colon compression. Practicing with multiple addresses — compressing them independently and then verifying against confirmed answers — is an effective way to internalize the rules and avoid common errors before working with IPv6 in live network environments or on certification exams.

What you'll learn

What's covered

IPv6 Address Compression

Aligned to

Cisco CCNA
1.8 Configure and verify IPv6 addressing and prefix
1.9 Describe IPv6 address types
Cisco CCST Networking
2.3 Identify IPv6 addresses and prefix formats
CompTIA Network+
3.4 Given a scenario, implement IPv4 and IPv6 network services

Key terms

IP Address
A numerical label assigned to each device connected to a network that uses the Internet Protocol.
IPv6
The sixth version of the Internet Protocol, using 128-bit addresses written in hexadecimal and separated by colons to provide a vastly larger address space than IPv4's 32-bit addresses. IPv6 also introduces built-in features like SLAAC, NDP, and mandatory support for IPsec.
Leading Zero Suppression
An IPv6 compression rule that allows leading zeros within any 16-bit group to be omitted.
Double-Colon Notation
An IPv6 compression rule represented by '::' that replaces one or more consecutive all-zero 16-bit groups, usable only once per address.

Transcript

Practicing IPv6 compression

We went over how we could compress these by removing some of the unnecessary zeros. We know that leading zeros are not necessary, because we can just assume that there are zeros there and not have a problem. Then we can also take a series of zeros and compress that down into just a colon colon, but we can only do that once.

So let's write this out. Compressing this into the colon colon, we can remove this zero and this zero out of there. I have to keep that 0 there, because that is going to be an important one. So 2001:db8:85a3::8a2e:370:7334. There is the answer.

Go through all of these, rewrite them, and then see how well you did. Here are the answers, so go ahead and check your answers. Hopefully you did that well; if not, go ahead and practice that before proceeding.

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