The main challenge facing IoT today is security. The constrained nature of IoT devices deprives them of using modern security solutions. This leads them to use aged and more vulnerable security mechanisms that expose them to high risks. When compared to more powerful devices, constrained IoT devices cannot use the Public Key Infrastructure with X.509 certificates to establish secure sessions. Moreover, the idea of self-signed certificates and having one trusted CA does not seem that popular. The Domain Name System (DNS) using the DNSbased Authentication of Named Entities protocol (DANE) and DNS's security extensions (DNSSEC) can help create the soughtafter Public Key Infrastructure (PKI) for IoT. With a concrete example, this article explains how DNS can deliver IoT PKI functions based on DANE, backed by DNSSEC.