In the ISC Bind9.11 named log, I get the following message:
debug 3: 184.108.40.206#13482: view red: request has valid signature: public-master-to-public-secondary
debug 3: 220.127.116.11#13482/key public-master-to-public-secondary: view red: recursion not available
debug 3: 18.104.22.168#13482/key public-master-to-public-secondary (MYDOMAIN.NET): view red: query 'mydomain.net/SOA/IN' approved
debug 3: 22.214.171.124#13482/key public-master-to-public-secondary (MYDOMAIN.NET): view red: reset client
Note: 126.96.36.199 is the out-of-band secdonary `slave.dns.he.net` DNS server that is performing the AXFR (pull) from my authoritative master DNS server (whose IP shall be left out for MYDOMAIN.NET)
Please notice the `recursion not available`.
1. Why is `slave.dns.he.net` performing a recursive querying?
2. And should we, the customers, be actually offering 'recursion' to this `slave.dns.he.net`?
3 Or is this a simple ISP test of ensuring that our customers' DNS server is NOT being "recursive" (having recursion enabled)?
Recursion is not needed for zone transfers. However, it could be set on the query that checks the SOA serial field, but certainly any extra data is not used. Having it set may be just an oversight.
Ohhhhtay. Looks like Hurricane Electric secondary updater (be that it may, the slave.dns.he.net or the ns1.he.net) is actually performing a full recursive querying on this customer's MYDOMAIN.NET hostname based, then taking the customer's (source) IP address and TSIG keyname to consult the "secondary HE customer" lookup database, as part of HE system design of "receive NOTIFY on one end, and AFXR on other end network process.
Perhaps, this HE secondary design of a simply querying of the customer's domain name could be refined then its DNS messaging exchange be broken up by actively going to each zone NS server (do a non-recursive query) and then heading to the next zone NS server (ad naseum) thereby avoiding any semblance of a recursion.
Unless there is another aspect to this split-highway update process and its usage of recursive querying that I am not aware of. But hey, what do I know. Just thinking outloud here.