"dig +trace" doesn't follow non-empty referrals

[Shumon Huque]

Hi folks,

I thought I'd check here before filing a bug in the gitlab repo -- in case
there is something I'm not understanding about dig's intended behavior.

"dig +trace" does not appear to be following referrals with a non-empty
answer section, e.g. with CNAMEs pointing below the zone cut. I tried this
with dig from several versions (9.11.x, 9.14.x, and 9.16.x) with the same
result.

Here's a real example (for brevity, I'm showing the last parts of the
output):

$ dig +trace dfw.salesforce.com. A
[...]
salesforce.com. 172800 IN NS udns1.salesforce.com.
salesforce.com. 172800 IN NS udns2.salesforce.com.
salesforce.com. 172800 IN NS udns3.salesforce.com.
salesforce.com. 172800 IN NS udns4.salesforce.com.
salesforce.com. 172800 IN NS pch1.salesforce-dns.com.
salesforce.com. 172800 IN NS pch2.salesforce-dns.com.
;; Received 444 bytes from 192.52.178.30#53(k.gtld-servers.net) in 7 ms

dfw.salesforce.com. 300 IN CNAME monitor-dfw.salesforce.com.
monitor-dfw.salesforce.com. 300 IN CNAME monitor-dfw.dfw.r.salesforce.com.
dfw.r.salesforce.com. 86400 IN NS ns1-dfw.salesforce.com.
;; Received 143 bytes from 156.154.100.8#53(udns1.salesforce.com) in 1 ms

The last response is above is a referral, but dig doesn't bother to follow
it and just terminates there.

Shumon Huque
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