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Issue description

This section actually teaches to use "ping6 -I eth0 fe80::4ee7:7805:6d16:16b5" for IPv6 link-local addresses, which is incorrect (yes, it technically works).

Even https://en.wikipedia.org/wiki/Link-local_address explains "When using an IPv6 link-local address to connect to a host, a zone index must be added to the address so that the packets can be sent out on the correct interface.".

So, practically, "ping fe80::4ee7:7805:6d16:16b5%eth0" is correct ("address%" is part of the IPv6 standard, because not each application allows to specify an interface). Note that ping(1) supports IPv6 since RHEL 8, so explicit ping6(1) is no longer needed (and if at all, there is the "-6" option matching with other command-line tools), seems to be an overleft from RHEL 6 or 7 in the course content.

I kindly ask you to revisit IPv6 scopes respectively IPv6 zones and to update this course content accordingly to be correct (as per RFCs) and modern (non-legacy).

See also e.g. https://labs.ripe.net/author/philip_homburg/whats-the-deal-with-ipv6-link-local-addresses from the RIPE NCC, one of the five Regional Internet Registries allocating IP addresses in the world.

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