[Yeti DNS Discuss] Out-of-bailiwick glue in the root zone

[Stephane Bortzmeyer]

On Thu, Aug 20, 2015 at 12:12:02PM +0800,
 Shane Kerr <shane at biigroup.cn> wrote 
 a message of 48 lines which said:

> The root zone has a bunch of out-of-bailiwick glue (also called
> "optional glue" some places).
...
> abb.           172800 IN NS   d5.nstld.com.
> d5.nstld.com.  172800 IN A    192.31.80.34
> 
> d5.nstld.com is under the .COM domain, and it is not glue for the .COM
> domain itself. As I understand it, a careful resolver will ignore
> this to avoid possibly corrupting its cache.

Unless all the .com name servers are under .abb and, then, optional
glue is no longer optional. AFAIK (disclaimer: I've never worked for
IANA, Verisign, the NTIA or the US Marines), this is why there are so
many "unnecessary glue" in the root: loops can be difficult to detect
(they may be several TLD long).

Of course, since IANA knows all the TLD and their name servers, they
could detect the loop and delete the really unnecessary glue (warning:
not so easy to program as it may seems), but I assume the zone
generator program do not implement such loop detection.