A stateful firewall is an advanced firewall that keeps track of the state of active connections, allowing it to make decisions based on the context of the traffic. It is more secure than a stateless firewall that filters packets based solely on static criteria like source and destination addresses.

They should consider a WAN (Wide Area Network). A WAN is designed to connect networks across a broad geographic area, which could include connecting multiple buildings in different locations, cities, or even countries. This is necessary for ensuring seamless communication between the two buildings.

An Intrusion Detection System (IDS) is a network security system that primarily focuses on detecting and alerting about potential threats and security breaches but does not actively block them. It monitors network traffic and system activities for suspicious behavior.

The combination of an IP address and a port number is often referred to as a "socket." Sockets are essential for directing data to the correct application or service on a machine in a network, enabling multiple applications to run on a single device and share the same IP address.

TCP (Transmission Control Protocol) primarily uses the three-way handshake to establish a connection between a client and a server. This process involves the client and server exchanging a series of messages to confirm and synchronize their communication, ensuring reliable data transfer.

The primary advantage of using a VPN (Virtual Private Network) when accessing public Wi-Fi hotspots is that it encrypts your data traffic, preventing potential eavesdropping and enhancing your privacy and security on open and potentially unsecured networks.

Mesh topology provides the highest fault tolerance due to its multiple connections. In a mesh network, every device is connected to every other device, ensuring redundancy. If one connection fails, traffic can be rerouted through other paths. This makes mesh topology highly fault-tolerant. However, it can be expensive and complex to set up due to the number of connections required.

The correct option is "Type." In Ethernet frame structure, the "Type" field specifies the type of protocol being used within the frame. This field helps network devices determine how to interpret the data within the frame, whether it's IP, ARP, or another protocol.

Quadrature Amplitude Modulation (QAM) is a modulation technique that combines both amplitude and phase modulation. It uses both amplitude and phase shifts to encode multiple bits per symbol, allowing for higher data rates and more efficient use of the spectrum. This is in contrast to basic amplitude or frequency modulation, which use only one of these characteristics for modulation.

In a MAC (Media Access Control) address, the first three octets are known as the OUI (Organizationally Unique Identifier), and they identify the manufacturer or organization that produced the network card. This allows for unique identification of devices on a network.