For a Class C Internet network, the default subnet mask is 255.255.255.0. This subnet mask allows for up to 256 IP addresses with 254 usable addresses for hosts (considering 1 address for the network and 1 for the broadcast address). It is the standard default subnet mask for Class C addresses.

The telnet protocol operates on Transmission Control Protocol (TCP) port number 23 by default. This port is used by Telnet server applications to listen for incoming connections. Port 25 is assigned to the Simple Mail Transfer Protocol (SMTP), port 80 to Hypertext Transfer Protocol (HTTP), and port 8080 is often used as an alternative to port 80 for HTTP services.

An 802.11g Internet connection operates on the 2.4 GHz band, which is also used by many household devices such as cordless phones and microwaves. These devices can cause interference and disrupt the connectivity of the network. Therefore, a cordless phone is a likely cause of connectivity problems in an 802.11g network.

A network perimeter is the boundary that separates an organization's private network from a public network. It is designed to protect internal systems and data from unauthorized access while allowing controlled communication with the external world.