The Multicast DNS (mDNS) specification is used for various commercial and consumer applications. This provides a benefit in that implementations exist, however, system administrators could choose to disable Multicast DNS operations. For this reason, Applications shall not rely on Multicast DNS capabilties.
Multicast DNS operations are insecure because of their nature; therefore they should be disabled in environments where an attacker could cause problems by impersonating another host. This risk is minimized if OPC UA security is enabled and all Applications use Certificate TrustLists to control access.