DNS URI records provide a way to associate Uniform Resource Identifiers (URIs) with domain names in the DNS. These records enable applications to discover services and resources associated with a domain by storing URI information directly in the DNS, facilitating service discovery and resource location.
URI records store a URI (such as a URL, email address, or other resource identifier) along with priority and weight values for service selection. These records are defined in RFC 7553 and provide a standardized way to publish resource locations in DNS, enabling applications to discover services and resources programmatically.
Each URI record contains a priority value (lower values are preferred), a weight value (for load balancing among records with the same priority), and the actual URI string. This structure allows for sophisticated service discovery with failover and load distribution capabilities.
Applications that support URI records can query DNS for these records to discover available services or resources for a domain. The application processes the priority and weight values to select the most appropriate URI, similar to how MX records work for email routing.
URI records are particularly useful for service discovery scenarios where you want to publish the location of web services, APIs, or other network resources. For example, a URI record might point to a RESTful API endpoint, a WebSocket server, or a download location for software updates.
While URI records provide standardized service discovery capabilities, their adoption has been limited compared to other service discovery mechanisms like SRV records or application-specific discovery protocols. However, they offer a clean, DNS-based approach to resource location that can be valuable in specific use cases.
Here's what a URI record looks like for the domain example.com:
