Rationale Behind Nonfunctional Requirements


if (newdp->d_cred > dp->d_cred) {
   /* better credibility.
    * remove the old datum.
   goto delete;


(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.