delegation NS records

[bind at zq3q.org]

Hi Bob:

These examples help!  Thank you.

On Thu 7/13/17 15:53 -0400 Bob Harold wrote:
> Let's illustrate one NS record, for each of the cases:
> (I think your case is #2)
> 
> 1. Name server name inside the domain itself
> 
> example.com zone:
> example.com IN NS ns.example.com
> ns.example.com IN A x.x.x.x
> 
> the TLD com would have (entered by the registrar)
> example.com IN  NS ns.example.com
> ns.example.com IN A x.x.x.x   (this is a "glue" record)

OK.  This example is the most commonly seen in web searches.

> 2. Name server name in another domain:
> 
> example.com zone:
> example.com IN NS ns.otherdomain.com
> 
> TLD com zone:
> example.com IN NS ns.otherdomain.com
> (no glue record)

Exactly one delegation NS record. 

Several have made that clear; ie I now clearly understand there is
*not* another NS delegation record needed in the zone with the $ORIGIN
that is part of the ("non vanity") nameserver's FQDN.

> otherdomain.com zone:
> ns.otherdomain.com IN A x.x.x.x

Almost goes without saying that  above A record is needed.

> 3. Sibling domains with name servers for each other: (should be avoided?)
> 
> example.com zone:
> example.com IN NS ns.otherdomain.com
> ns.example.com IN A x.x.x.x
> 
> otherdomain.com zone:
> otherdomain.com IN  NS ns.example.com
> ns.otherdomain.com IN A x.x.x.x
> 
> TLD com zone:
> example.com IN NS ns.otherdomain.com
> ns.example.com IN A x.x.x.x  (glue record?)
> ns.otherdomain.com IN A x.x.x.x (glue record?)

Interesting.  I think the glue record make sense.
I'm not planning to do this. :->

I do not see any delegation NS record for otherdomain.com above.
Is this right?:

    TLD com zone:
    example.com        IN NS ns.otherdomain.com
    ns.example.com     IN A x.x.x.x  (glue record?)
    otherdomain.com    IN NS ns.example.com
    ns.otherdomain.com IN A x.x.x.x (glue record?)
    
--
thanks,
Tom