simplex need not advertise server dns or IP at all - completely wrong someonce can attack private server - yes only dns exposed can be attacked nobody knows who is running nostr relay also - gov harvesting via relay too or nostr:npub1xtscya34g58tk0z605fvr788k263gsu6cy9x0mhnm87echrgufzsevkk5s can forced to be secret service also - that why everyone run own relay. that whole point no need know who running relay or server