DDNS: fix condition to check if RR belongs into a zone

src/knot/updates/ddns.c

@@ -189,7 +189,8 @@ static int process_prereq(const knot_rrset_t *rrset, uint16_t qclass,
 		return KNOT_EMALF;
 	}
 
-	if (!knot_dname_is_sub(rrset->owner, update->zone->apex->owner)) {
+	if (!knot_dname_is_equal(rrset->owner, update->zone->apex->owner) &&
+	    !knot_dname_is_sub(rrset->owner, update->zone->apex->owner)) {
 		*rcode = KNOT_RCODE_NOTZONE;
 		return KNOT_EOUTOFZONE;
 	}