Get the display name.

@example Get the display name.

  Unknown.display_name

@return [ String ] The display name.

@since 2.0.0

Determine if the topology would select a readable server for the provided candidates and read preference.

@example Is a readable server present?

  topology.has_readable_server?(cluster, server_selector)

@param [ Cluster ] cluster The cluster. @param [ ServerSelector ] server_selector The server

  selector.

@return [ false ] An Unknown topology will never have a readable server.

@since 2.4.0

Determine if the topology would select a writable server for the provided candidates.

@example Is a writable server present?

  topology.has_writable_server?(servers)

@param [ Cluster ] cluster The cluster.

@return [ false ] An Unknown topology will never have a writable server.

@since 2.4.0

An unknown topology is not a replica set.

@example Is the topology a replica set?

  Unknown.replica_set?

@return [ false ] Always false.

@since 2.0.0

Select appropriate servers for this topology.

@example Select the servers.

  Unknown.servers(servers)

@param [ Array<Server> ] servers The known servers.

@raise [ Unknown ] Cannot select servers when the topology is

  unknown.

@since 2.0.0

An unknown topology is not sharded.

@example Is the topology sharded?

  Unknown.sharded?

@return [ false ] Always false.

@since 2.0.0

An unknown topology is not single.

@example Is the topology single?

  Unknown.single?

@return [ true ] Always false.

@since 2.0.0

@note This method is experimental and subject to change.

@api experimental @since 2.7.0

An unknown topology is unknown.

@example Is the topology unknown?

  Unknown.unknown?

@return [ true ] Always true.

@since 2.0.0