Rationale Behind Nonfunctional Requirements
Code
if (newdp->d_cred > dp->d_cred) {
/* better credibility.
* remove the old datum.
*/
goto delete;
}
Documentation
(P. Vixie's BIND Security Paper)
5.1. Cache Tagging
BIND now maintains for each cached RR a "credibility" level showing
whether the data came from a zone, an authoritative answer, an authority
section, or additional data section. When a more credible RRset comes in,
the old one is completely wiped out. Older BINDs blindly aggregated data
from all sources, paying no attention to the maxim that some sources
are better than others.