Server Attributes

These attributes may be used to describe the server in a connection-based network interaction where there is one side that initiates the connection (the client is the side that initiates the connection). This covers all TCP network interactions since TCP is connection-based and one side initiates the connection (an exception is made for peer-to-peer communication over TCP where the “user-facing” surface of the protocol / API does not expose a clear notion of client and server). This also covers UDP network interactions where one side initiates the interaction, e.g. QUIC (HTTP/3) and DNS.

Attribute	Type	Description	Examples	Stability
server.address	string	Server domain name if available without reverse DNS lookup; otherwise, IP address or Unix domain socket name. [1]	example.com; 10.1.2.80; /tmp/my.sock
server.port	int	Server port number. [2]	80; 8080; 443

[1]: When observed from the client side, and when communicating through an intermediary, server.address SHOULD represent the server address behind any intermediaries, for example proxies, if it’s available.

[2]: When observed from the client side, and when communicating through an intermediary, server.port SHOULD represent the server port behind any intermediaries, for example proxies, if it’s available.