A non-transitory computer readable medium storing instructions readable by a computer comprising a communication interlace configured communicable with a server device and a name resolution server,
- the server device being configured to store an operation system configured communicable based upon an IPv4 communication protocol and IPv6 communication protocol and two or more application programs configured operable on the operation system,
- the name resolution server being configured to store an IPv4 address and an IPv6 address that enable communication on the operation system of the server device and a device name of the server device associated with each other, and upon receiving the device name from a requesting source requesting an IP address, send the IPv4 address and the IPv6 address corresponding to the received device name to the requesting source,
- the instructions, when executed by the computer, causing the computer to serve as:
- a sending and receiving system configured to send the device name of the server device to the name resolution server, and receive the IPv4 address and IPv6 address corresponding to the device name that are to be sent from the name resolution server;
- an IP address storing system configured to store the IPv4 address and the IPv6 address received by the sending and receiving system;
- an access system configured to access the application programs of the server device;
- an access control system configured to control the access system to access the application programs of the server device according to the IPv4 address and the IPv6 address stored in the IP address storing system;
- a communication protocol storing system configured to store one of the IPv4 communication protocol and the IPv6 communication protocol that corresponds to one of the IPv4 address and the IPv6 address used for a previous successful access by the access system to a corresponding one of the application programs of the server device, for each of the application programs of the server device;
- and
- an access control instructing system configured to instruct the access control system to control the access system to access a corresponding one of the application programs of the server device in accordance with the one of the IPv4 address and the IPv6 address stored in the IP address storing system that corresponds to the one of the IPv4 communication protocol and the IPv6 communication protocol stored in the communication protocol storing system,
- wherein the access control instructing system is configured to instruct the access control system to control the access system to access an application program of the server device again using one of the IPv4 address and the IPv6 address corresponding to one of the IPv4 communication protocol and the IPv6 communication protocol different from the one of the IPv4 communication protocol and the IPv6 communication protocol stored in the communication protocol storing system, in response to the application program of the server device being inaccessible in accordance with the one of the IPv4 address and the IPv6 address corresponding to the one of the IPv4 communication protocol and the IPv6 communication protocol stored in the communication protocol storing memory.