The IETF (Internet Engineering Task Force), which is responsible for developing internet protocols and architecture, The formation of RFC for the "DNS Push Notifications" mechanism and the publication of the associated specification under the identifier . The RFC has received the status of 'Proposed Standard', after which work will begin to elevate the RFC to Draft Standard status, effectively meaning the full stabilization of the protocol and consideration of all expressed comments.
The "DNS Push Notification" mechanism enables clients to receive notifications asynchronously from the DNS server regarding changes in DNS records, without the need for periodic polling. Push notifications are processed only using TCP transport with secure communication via "TLS over TCP." The authoritative DNS server can accept TCP connections from DNS Push Notification clients sending subscription requests for specific names and types of DNS records. After receiving a subscription request, the server will send notifications to the client about changes to the specified records.
The client determines the support for DNS Push Notification by sending a regular DNS query to check for the existence of an SRV record "_dns-push-tls._tcp.zone_name," which points to DNS servers handling subscriptions. The client can also subscribe to a non-existent record, and the server must notify the client if it appears in the future. Notifications are sent only when a TCP connection with the server is established and are not intended for 24/7 tracking — the subscription should be canceled during inactivity (for example, when the device enters sleep mode) and used only when there is a direct need for live change tracking. Regular DSN queries can also be sent through the established TCP channel for Push notifications.
Source: opennet.ru
