A mobile communication system comprising: a plurality of EPC nodes (102, 103, 104, 105) that are configured to form an EPC (Evolved Packet Core) network, the EPC network forming a core of an LTE (Long Term Evolution) network for mobile communication; and a DNS server that is configured to select the EPC node to use among the plurality of EPC nodes based on a selection priority in a DNS (Domain Name Server) resource record that is registered, wherein each of the plurality of EPC nodes (102, 103, 104, 105) includes a DDNS (Dynamic DNS) client function that is configured to transmit an update request for the DNS resource record to the DNS server in order to lower the selection priority of the DNS resource record relating to the EPC node when the EPC node detects that resource usage of the own EPC node exceeds an overloaded threshold previously specified to detect that the resource usage of the own EPC node is approaching to an overloaded state, and the DNS server includes a DDNS server function that is configured to dynamically update in response to the update request, the DNS resource record when the DNS server receives the update request for the DNS resource record from the EPC node; wherein the DNS server further includes as the DNS resource record, in addition to an NAPTR (Naming Authority Pointer) record and an SRV (Service) record to which the selection priority is registered, a supplementary NAPTR record to which a domain name of the DNS resource record relating to the EPC node allocated with the EPC node name is previously set, and when the DNS server receives an NAPTR record query including the EPC node name of the own EPC node from the EPC node, the DNS server is configured to extract at least the supplementary NAPTR relating to the EPC node name included in the NAPTR record query and return the extracted supplementary NAPTR to the querying EPC node. a plurality of EPC nodes (102, 103, 104, 105) that are configured to form an EPC (Evolved Packet Core) network, the EPC network forming a core of an LTE (Long Term Evolution) network for mobile communication; and a DNS server that is configured to select the EPC node to use among the plurality of EPC nodes based on a selection priority in a DNS (Domain Name Server) resource record that is registered, wherein each of the plurality of EPC nodes (102, 103, 104, 105) includes a DDNS (Dynamic DNS) client function that is configured to transmit an update request for the DNS resource record to the DNS server in order to lower the selection priority of the DNS resource record relating to the EPC node when the EPC node detects that resource usage of the own EPC node exceeds an overloaded threshold previously specified to detect that the resource usage of the own EPC node is approaching to an overloaded state, and the DNS server includes a DDNS server function that is configured to dynamically update in response to the update request, the DNS resource record when the DNS server receives the update request for the DNS resource record from the EPC node; wherein the DNS server further includes as the DNS resource record, in addition to an NAPTR (Naming Authority Pointer) record and an SRV (Service) record to which the selection priority is registered, a supplementary NAPTR record to which a domain name of the DNS resource record relating to the EPC node allocated with the EPC node name is previously set, and when the DNS server receives an NAPTR record query including the EPC node name of the own EPC node from the EPC node, the DNS server is configured to extract at least the supplementary NAPTR relating to the EPC node name included in the NAPTR record query and return the extracted supplementary NAPTR to the querying EPC node.