Sage Test - Glue Records for my domain, not my MX record target

[nfawcett]

I'm a bit confused.  The domain I chose to certify with is "fallingwithouta.net".  The IPv6 capable MX record points to "ipv6.fallingwithouta.net".  During the Sage test, it states "To complete the Sage Test you will need the authoritative nameservers for your domain, ipv6.fallingwithouta.net have IPv6 glue at the registrar".   "ipv6" is not a subdomain, it's a host.  Am I crazy?  The only place there would be glue records is at the parent domain of mine (which is "net"), and they're actually not needed there because my nameservers are under the "com" TLD.