DNS_MESSAGEEXTFLAG_DO
pack_u16(p, dnssec_do ? DNS_MESSAGEEXTFLAG_DO : 0);
flags &= ~DNS_MESSAGEEXTFLAG_DO;
flags |= DNS_MESSAGEEXTFLAG_DO;
#define DNS_MESSAGEEXTFLAG_REPLYPRESERVE (DNS_MESSAGEEXTFLAG_DO)
if ((ps->ttl & DNS_MESSAGEEXTFLAG_DO) != 0)
mbz &= ~DNS_MESSAGEEXTFLAG_DO; /* Known Flags. */