Global unicast IPv6 addresses are designed to be reachable anywhere on the Internet. They are globally routable, assigned in blocks by regional registries, and intended for hosts that need public reachability across networks. This makes packets with these addresses forwardable across the global routing system. In contrast, an address used only on the local link isn’t routable beyond that single network segment, multicast addresses target multiple destinations, and private (ULA) addresses aren’t meant for global Internet reachability. So the defining trait is that it is globally routable.

Port security controls which devices can use a switch port by binding specific MAC addresses to that port, limiting how many unique addresses can send frames. If a frame from a MAC address that isn’t allowed appears, or if the number of allowed addresses is exceeded, the switch can take a violation action, most commonly shutting the port down to prevent access. This helps protect the network from unauthorized devices and MAC spoofing. It does not encrypt traffic, does not allow every MAC address to connect, and does not dynamically change the VLAN on the port.

Software as a Service is being demonstrated. Migrating on-premises email to a cloud-hosted email service means you’re using a ready-made email application that runs on the provider’s infrastructure and is accessed over the internet. You don’t manage or install the software, the servers, the storage, or the operating system; the provider handles maintenance, updates, and security. You simply use the email service, paying for and configuring it at a user level. This differs from Platform as a Service, where you’re given a platform to develop or deploy your own applications, and from Infrastructure as a Service, where you rent virtual machines and recreate the stack yourself. DaaS would not fit this scenario, since the focus is on using a software application (email) rather than delivering a desktop or data service.

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.