Question on TTLs
I have run into some shenanigans where vendors are using load balancers or spilit brain DNS to provide an A record response sometimes and a CNAME response at other times for the same hostname.
Doing this is against the CNAME and other data, but functions because its not being done on the same DNS servers.
The issue becomes sometimes my DNS server asks for the CNAME instead of the A record and if that happens against the servers providing the A record I get NOERROR/NODATA as would be expected.
As I try to determine what is the trigger for BIND specifically requesting the CNAME rather than the A, I am looking toward cache timers and need to understand which TTL is used on a NOERROR/NODATA response. Is it the "positive" TTL like on a successful query with an answer section, is it the ncache TTL used on nxdomain, or something else entirely?
I ask because when this occurs the client my network who wants the name can take a while to recover.