Delegating /24's from a /19

Bruce Campbell bc-nanog at
Tue Mar 15 21:33:39 UTC 2005

On Tue, 15 Mar 2005, Robert Blayzor wrote:

> alex at wrote:
> > Either by doing DNS delegation on the zone boundary or by SWIP'ing the
> > space to the other company.
> You can SWIP it yes, but that won't help DNS on small blocks like /24's.


Unless I've missed something really obvious, the original requestor has a
/19 allocation, say .  ARIN has DNS-delegated this to the
original requestor as a series of /24s, eg:,		ditto
		...		ditto		ditto

There are two solutions.

One, he secondaries the appropriate domain from the customers nameservers
onto his nameservers.  Very easy, since the delegation already points to
his nameservers, and he can market this as 'the domain is there even if
you are disconnected!'.

Or two, he creates a seperate netblock in the ARIN registry describing the
customer's /24, and nominates their nameservers instead of his, listing
his nameservers as backup just in case.  ARIN change the DNS delegation at
their next zone generation.

Or third, he describes the situation to a friendly ARIN representative,
who ought to give the above solutions, as well as suggest getting the DNS
& Bind book from O'Reilly for bedtime reading.


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