[DICKSON KASANO]

IPv6 is the internet’s updated addressing system, providing a virtually infinite supply of unique IDs to replace the exhausted IPv4 protocol.
It is necessary because the original 4.3 billion address limit cannot support the billions of smartphones and smart devices now online.
The upgrade streamlines connectivity by allowing direct device communication, improving routing efficiency, and providing stronger built-in security.

[DICKSON KASANO]

That is a great way to frame the paradigm shift between the two protocols. You’ve hit on the core philosophical difference in how address space is managed.

In IPv4, we are constantly fighting address scarcity. We use Variable Length Subnet Masking (VLSM) to “right-size” a subnet, often trying to find the smallest mask—like a $/30$ for a point-to-point link—to avoid wasting any of the 4.2 billion available addresses.

In IPv6, the “scarcity mindset” is replaced by a “hierarchy mindset.” Here is why the focus shifts entirely to the subnet:

[DICKSON KASANO]

same here

[DICKSON KASANO]

well explained

[DICKSON KASANO]

In macOS, IPv6 privacy addresses are split into two categories with different persistence behaviors: <b data-path-to-node="”0″" data-index-in-node="”101″">Temporary Addresses are strictly non-persistent and rotate approximately every 24 hours to prevent long-term web tracking, while <b data-path-to-node="”0″" data-index-in-node="”230″">Stable Privacy Addresses (labeled as “secured”) are persistent as long as you remain connected to the same network. This dual-layer approach ensures that while your outgoing web traffic uses a constantly changing identity, your device maintains a consistent “stable” address for local network services without ever revealing your hardware’s actual MAC address. Consequently, the address you use to browse the internet will change daily, but the address used for local identification will only change when you move to a different Wi-Fi SSID.

[DICKSON KASANO]

The IPv4 base header has a minimum size of <b data-path-to-node="”0″" data-index-in-node="”43″">20 bytes and a maximum size of <b data-path-to-node="”0″" data-index-in-node="”74″">60 bytes. The reason it varies is due to the <b data-path-to-node="”0″" data-index-in-node="”119″">Options field, which is rarely used but can add up to 40 additional bytes to the header.

[DICKSON KASANO]

Global Unicast Addresses are used for anycast because they are the only address type with a global scope and full routability via the Border Gateway Protocol (BGP). Link-Local addresses are unsuitable because they are restricted to a single local network and cannot be routed across the internet, preventing the “nearest server” selection that anycast requires. Multicast addresses are also disqualified because they are designed for one-to-many delivery, whereas anycast is specifically a one-to-one-of-many delivery where only the single closest destination responds. By using Global Unicast Addresses, multiple servers in different geographic regions can advertise the exact same IP prefix, allowing the global routing table to efficiently direct traffic to the closest physical instance based on the shortest network path

[DICKSON KASANO]

i stil dont get it

[DICKSON KASANO]

Your shortened form <b data-path-to-node="”0″" data-index-in-node="”20″">2001:db8::ff00:42:29 is perfectly correct because you accurately applied the zero-compression rules. The most critical mistake to avoid is using the double colon (::) more than once in a single address; doing so creates ambiguity, as a computer wouldn’t know how many zeros to re-insert into each section. Another common pitfall is accidentally removing trailing zeros, such as turning <code data-path-to-node="”0″" data-index-in-node="”406″">ff00 into <code data-path-to-node="”0″" data-index-in-node="”416″">ff, which fundamentally changes the numerical value of the block. You must also ensure that when you aren’t using the double colon, a block of four zeros is reduced to a single <code data-path-to-node="”0″" data-index-in-node="”593″">0 rather than being deleted entirely. Many beginners also struggle with the distinction between hexadecimal and decimal, forgetting that letters A-F are valid digits in this 128-bit system. Finally, always verify that your shortened address can be expanded back to exactly eight blocks to confirm you haven’t lost any data. By strictly following these constraints, you ensure the address remains technically valid and readable across all networking hardware.

[DICKSON KASANO]

The shortened version of your address is <b data-path-to-node="”0″" data-index-in-node="”41″">2001:db8::ff00:42:29, which is achieved by stripping away redundant data.
First, leading zeros are removed from each block, turning <code data-path-to-node=”0″ data-index-in-node=”173″>0db8 into <code data-path-to-node=”0″ data-index-in-node=”183″>db8 and <code data-path-to-node=”0″ data-index-in-node=”191″>0042 into just <code data-path-to-node=”0″ data-index-in-node=”206″>42.
Next, the three consecutive blocks of total zeros (<code data-path-to-node=”0″ data-index-in-node=”261″>0000:0000:0000) are collapsed into a single double-colon <code data-path-to-node=”0″ data-index-in-node=”318″>::.
It is important to leave trailing zeros like the ones in <code data-path-to-node=”0″ data-index-in-node=”379″>ff00 alone, as they represent the value of that specific block.
This logic keeps the address concise while ensuring it can always be expanded back to its full 128-bit form.

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Understand and Work with IPv6 Addresses - IPv6 Foundations - AFRINIC | Learning Hub

Understand and Work with IPv6 Addresses - IPv6 Foundations - AFRINIC | Learning Hub