Cisco Certified Entry Networking Technician (CCENT) Practice Exam

The main idea is that a router builds a directly connected network from the IP address and the subnet mask configured on the interface. For a classful Class B network, 172.16.0.0 uses the default /16 mask (255.255.0.0). When you configure an interface with an address that falls inside 172.16.0.0/16 and use a /16 mask, the router computes the network as 172.16.0.0/16, creating a connected route for the entire classful network. Configuring 172.16.1.1 with a /16 mask does exactly this: the network becomes 172.16.0.0/16, so the router has a connected route to the whole 172.16.0.0/16 block. In contrast, a /24 mask would split into smaller networks (like 172.16.1.0/24 or 172.16.0.0/24), not the entire 172.16.0.0/16 block, and a /32 mask would only reference a single host. So the address that best creates a connected route for the entire 172.16.0.0/16 is the one with the /16 mask.