Hi. I have a primary name server at my location, we'll call it ns1.mydomain.com. Then, I have 2 backup DNS servers we'll call ns1.someotherdomain.com and ns2.someotherdomain.com., which do zone pulls to obtain their records from my nameserver. My question is, on ns1.mydomain.com, how would I configure glue records for my secondary nameservers since they're not a part of my domain? Is it even necessary?