Delegating Part Of Class C?

[Joseph S D Yao]

One problem is, you're representing the first parts as xxx.xxx.xxx, so
I can't tell whether you are correctly reversing the parts of the IP
address or not.

If I have a subnet 120.110.100.80/29, then my ISP would have reverse
DNS zone:

	100.110.120.in-addr.arpa

within which the hostmasters might delegate:

	80-29		IN  NS		name.server.your.domain
;	80		IN  CNAME	80.80-29	- network
	81		IN  CNAME	81.80-29
	...
	86		IN  CNAME	86.80-29
;	87		IN  CNAME	87.80-29	- broadcast

I would then have a local domain

	80-29.100.110.120.in-addr.arpa

within which I would designate:

	81		IN  PTR		host1.your.domain.
	82		IN  PTR		host2.your.domain.
	...
	86		IN  PTR		host6.your.domain.

Now, note: I  m u s t  let the ISP manage network
100.110.120.in-addr.arpa!  And I must have access to external DNS.  If
either of these is changed, then I  w i l l   n o t  be able to resolve
[e.g.] 81.100.110.120.in-addr.arpa, which I take it is your current
problem.

But, let's say that we have external DNS, and are NOT pretending to
manage 100.110.120.in-addr.arpa.  Then, when we want to resolve
81.100.110.120.in-addr.arpa, we must go back to the root servers [or
however far back] and find that the universally acclaimed authority on
the 100.110.120.in-addr.arpa domain is ... the ISP!  The ISP modestly
says, well, yes, but for 81.100.110.120.in-addr.arpa, you must check
under 81.80-29.100.110.120.in-addr.arpa; and, oh, by the way, the
authority for the 80-29.100.110.120.in-addr.arpa domain is
name.server.your.domain ... and then it's over to you.

Capish?

[Incidentally, there is nothing magic about "80-29" except that it
 captures the essentials of your subnet.  Your provider apparently
 prefers to use just "80", which is possibly confusing.]

Where are you in disharmony with this model?

--
Joe Yao				jsdy at cospo.osis.gov - Joseph S. D. Yao
COSPO/OSIS Computer Support					EMT-B
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