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From: Koen Martens <in+usenet@metro.cx>
Newsgroups: comp.os.linux.advocacy
Subject: Re: Anybody Using IPv6?
Date: Sat, 17 May 2025 08:02:05 +0200
Organization: Sonologic AB
Message-ID: <10098ot$1epk$2@nntp.sonologic.net>
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Den 2025-05-16 kl. 21:17, skrev rbowman:
> True, but it's not a problem in my local WiFi network. I suppose I could
> put the fours or five machines in the hosts file. At work there is DNS so
> using host names work but at times it's handy to know what subnet a
> machine is on. If you can do that from a IPv6 address I've never figured
> it out.

It's pretty much the same with IPv6 as it was with IPv4, it's just that 
the numbers are bigger.

Where in IPv6 you have 32 bits, in IPv4 it's 128. The most common (and 
in fact, prescribed for local networks) subnet in IPv6 is a /64, so 
exactly half of the 128 bits.

Also, the 128 bits are written in groups of 16 bits (or four hex 
digits), separated by colons. One such bit of 16 bits is called a hextet.

So if I'd have an address 2a0a:4580:103f:c0de::1 (which is just another 
way of writing 2a0a:4580:103f:c0de:0:0:0:1) in a /64, the subnet would 
be the first 64 bits = 4 hextets, ie 2a0a:4580:103f:c0de::/64.

If I have a more elaborate IPv6 address, such as 
2a0a:4580:103f:c0de:da7f:7136:fbd6:e64d/64, it's still simple: split up 
in the middle and you have your subnet (or 'routing prefix' in IPv6 
lingo): 2a0a:4580:103f:c0de::/64.

Cheers,

Koen

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