What the heck is that %xx at the end of my IPv6 address when I IPCONFIG /ALL and get my link local address??

taken from here…

IPv6 wikipedia info

Link-local addresses and zone indices

All interfaces have an associated link-local address, that is only guaranteed to be unique on the attached link. Link local addresses are defined by the address prefix fe80::/10, with the only allocated subnet (54 bits) being zero, such that a standards-based link-local address has an effective format fe80::/64. The least significant 64 bits are usually chosen as the interface hardware address constructed in modified EUI-64 format.

Because all link-local addresses in a host have a common prefix,
normal routing procedures cannot be used to choose the outgoing
interface when sending packets to a link-local destination. A special
identifier, known as a zone index, is needed to provide the
additional routing information; in the case of link-local addresses,
zone indices correspond to interface identifiers.

When an address is written textually, the zone index is appended to the address, separated by a percent sign "%". The actual syntax of zone indices depends on the operating system:

  • the Microsoft Windows IPv6 stack uses numeric zone indexes, e.g., fe80::3%1. The index is determined by the interface number.
  • Some Unix-like systems (e.g., BSD and Linux) use the interface name as a zone index: fe80::3%eth0.
  • Mac OS X (10.5.7) also uses the interface name (e.g. en0) as a zone index: fe80::3%en0.

Zone index notations cause syntax conflicts when used in Uniform Resource Identifiers (URI), as the ‘%’ character also designates percent-encoding.[16]

Relatively few IPv6-capable applications
understand address scope syntax at the user level, thus rendering
link-local addressing inappropriate for many user applications.
However, link-local addresses are not intended for most of such
application usage and their primary benefit is in low-level network
management functions[citation needed], for example for logging into a router that for some reason has become unreachable.

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