A service access apparatus arranged to selectively initiate communication with a network node providing a service, the service access apparatus comprising: a data obtainer arranged to: obtain a multilevel hierarchical identifier associated with a user of the service access apparatus, wherein the multilevel hierarchical identifier is structured from one of a higher level to a lower level and the lower level to the higher level; determine whether a hierarchy of the multilevel hierarchical identifier differs from being structured with the lower level first; in response to the determination, perform one of: reverse the multilevel hierarchical identifier such that the multilevel hierarchical identifier is structured with the lower level first, when the hierarchy of the multilevel hierarchical identifier differs from being structured with the lower level first; and retain the multilevel hierarchical identifier being structured with the lower level first, when the hierarchy of the multilevel hierarchical identifier is structured with the lower level first; a concatenator arranged to determine a combined domain name by concatenating the multilevel hierarchical identifier and a domain name of the network node, wherein the multilevel hierarchical identifier being concatenated is one of the reversed multilevel hierarchical identifier and the retained multilevel hierarchical identifier; a domain name lookup client arranged to perform a domain name lookup using the combined domain name, and receive a response of the domain name lookup; and a communication initiator arranged to, when the response comprises a valid resource record for the network node, initiate the communication with the network node using a node pointer in the valid resource record. a data obtainer arranged to: obtain a multilevel hierarchical identifier associated with a user of the service access apparatus, wherein the multilevel hierarchical identifier is structured from one of a higher level to a lower level and the lower level to the higher level; determine whether a hierarchy of the multilevel hierarchical identifier differs from being structured with the lower level first; in response to the determination, perform one of: reverse the multilevel hierarchical identifier such that the multilevel hierarchical identifier is structured with the lower level first, when the hierarchy of the multilevel hierarchical identifier differs from being structured with the lower level first; and retain the multilevel hierarchical identifier being structured with the lower level first, when the hierarchy of the multilevel hierarchical identifier is structured with the lower level first; obtain a multilevel hierarchical identifier associated with a user of the service access apparatus, wherein the multilevel hierarchical identifier is structured from one of a higher level to a lower level and the lower level to the higher level; determine whether a hierarchy of the multilevel hierarchical identifier differs from being structured with the lower level first; in response to the determination, perform one of: reverse the multilevel hierarchical identifier such that the multilevel hierarchical identifier is structured with the lower level first, when the hierarchy of the multilevel hierarchical identifier differs from being structured with the lower level first; and retain the multilevel hierarchical identifier being structured with the lower level first, when the hierarchy of the multilevel hierarchical identifier is structured with the lower level first; reverse the multilevel hierarchical identifier such that the multilevel hierarchical identifier is structured with the lower level first, when the hierarchy of the multilevel hierarchical identifier differs from being structured with the lower level first; and retain the multilevel hierarchical identifier being structured with the lower level first, when the hierarchy of the multilevel hierarchical identifier is structured with the lower level first; a concatenator arranged to determine a combined domain name by concatenating the multilevel hierarchical identifier and a domain name of the network node, wherein the multilevel hierarchical identifier being concatenated is one of the reversed multilevel hierarchical identifier and the retained multilevel hierarchical identifier; a domain name lookup client arranged to perform a domain name lookup using the combined domain name, and receive a response of the domain name lookup; and a communication initiator arranged to, when the response comprises a valid resource record for the network node, initiate the communication with the network node using a node pointer in the valid resource record.