Re: Federated, decentralised communication on the internet

[Dan Purgert <dan@djph.net>]

Richard Hector wrote:
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> From: Richard Hector <richard@walnut.gen.nz>
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> Subject: Re: Federated, decentralised communication on the internet
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> On 23/03/18 11:31, Dan Purgert wrote:
>> Richard Hector wrote:
>>> On 23/03/18 01:17, Greg Wooledge wrote:
>>>> [...]
>>>> RFC 1594 <https://tools.ietf.org/html/rfc1594>: A Fully Qualified
>>>> Domain Name (FQDN) is a domain name that includes all higher level
>>>> domains relevant to the entity named.  If you think of the DNS as a
>>>> tree-structure with each node having its own label, a Fully Qualified=
>
>>>> Domain Name for a specific node would be its label followed by the
>>>> labels of all the other nodes between it and the root of the tree.
>>>>
>>>> For example, for a host, a FQDN would include the string that
>>>> identifies the particular host, plus all domains of which the host is=
>
>>>> a part up to and including the top-level domain (the root domain is
>>>> always null).
>>>
>>> Thanks - Having read that paragraph of the RFC, it doesn't seem to
>>> require any particular number of levels, only that all that exist are
>>> present.
>>>
>>> Richard
>>=20
>> It requires two "levels"
>>=20
>>  1. the TLD itself
>>  2. the named host
>>=20
>> Therefore, "com." (that is, the TLD 'com') is not a valid FQDN. However=
> ,
>> "a.com." (that is, the host 'a' on the 'com' TLD) is a valid FQDN.
>
> That's not what I see in the RFC. The DNS only seems to care about a
> tree of nodes with labels, not whether a particular node represents a
> host or a network or something else. So if the node in question has the
> label "com", and "All the other nodes" consist of just the root domain
> (with the null label), that should be sufficient. Even just the null
> label followed by (empty list) should be enough. What you say may well
> be what was intended, but it doesn't seem specific to me.

You seem to be considering a "node" as representing more than it
actually is -- a node cannot simultaneously be "a named entity" AND ALSO
a grouping. 

I suppose we can consider a FQDN to be somewhat like a mailing address:

"country" is the root (though unlike DNS, it's "optional" information -
  if not specified "the country of origin" is assumed)
"zipcode" is the TLD
"state" is the domain
"city" is a subdomain
"street address" is another subdomain
"addressed individual" is the entity.


This isn't a valid address:

    USA

Nor is anything up to and including

    123 Main Street
    Anytown, Anystate  90210

Which is why all of your bulk mail is sent to something like

    Current Resident
    your_address
    your_city, your_state zipcode

Likewise, "com" is not a FQDN, since it doesn't name a specific entity
that is part of the "com" top-level domain.  

On the other hand, "lists.debian.org" is fully qualified for the
specific host "lists" of the "debian" domain of the "org" TLD. However,
"lists.debian" is not a FQDN, as it does not ultimately point to a valid
TLD.


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