A BIND 9.x server validity period for the RRSIGs covering a zones DNSKEY RRSet must be no less than two days and no more than one week.

The best way for a zone administrator to minimize the impact of a key compromise is by limiting the validity period of RRSIGs in the zone and in the parent zone. This strategy limits the time during which an attacker can take advantage of a compromised key to forge responses. An attacker that has compromised a zone signing key (ZSK) can use that key only during the key signing key's (KSK's) signature validity interval. An attacker that has compromised a KSK can use that key for only as long as the signature interval of the RRSIG covering the DS RR in the delegating parent. These validity periods should be short, which will require frequent re-signing.