The primary purpose of the Session Layer is to establish, manage, and terminate sessions between applications.

The primary role of a router is to filter traffic based on IP addresses and route packets between different networks.

The primary role of the Presentation layer is to format and translate data, including encryption and decryption.

A router routes traffic between different networks, making decisions based on IP addresses.

A switch connects devices within the same network and uses MAC addresses to forward data to the correct destination.

A VLAN (Virtual Local Area Network) is used to segment network traffic, allowing for better management and isolation of different network segments.

Cookies are used to store user preferences, track sessions, and authenticate users across web applications.

Error control is used to ensure data integrity by detecting and correcting errors that may occur during transmission.

HTTP headers are used to provide metadata about the request or response, such as content type and length.

Subnetting divides a larger network into smaller, manageable segments, improving performance and security by limiting broadcast domains.

The 'Cache-Control' header specifies caching policies for responses, helping to control how and for how long responses are cached by clients and intermediaries.

The 'Content-Type' header indicates the media type of the resource being sent in the HTTP response, helping the client understand how to process it.

The 'User-Agent' header is used to identify the client software making the request, providing information about the browser and operating system.

The default gateway routes traffic from a local network to destinations outside that network, typically between subnets.

The Cache-Control header is used to specify directives for caching mechanisms in both requests and responses.

The HTTP POST method is used to send data to the server, often resulting in a change in state or side effects on the server.

The HTTP status code 404 indicates that the requested resource was not found on the server.

The Network Layer (Layer 3) is responsible for routing packets across different networks and managing logical addressing.

The network portion of an IP address identifies the specific network to which the device belongs.

The Physical Layer (Layer 1) is responsible for the transmission of raw bitstreams over a physical medium, including electrical signals and light pulses.

The subnet mask determines which part of an IP address refers to the network and which part refers to the host.

Subnetting enhances security and manageability by creating smaller, isolated networks that can be controlled more effectively.

Subnetting helps create more broadcast domains, reduces routing table size, and enhances security and performance.

In the subnet 192.168.1.0/24, the valid host addresses range from 192.168.1.1 to 192.168.1.254, as 192.168.1.0 is the network address and 192.168.1.255 is the broadcast address.

A web server processes HTTP requests and serves the requested content to clients.

The 'User-Agent' header in an HTTP request identifies the client software making the request, allowing the server to tailor responses accordingly.

A Class C address with 30 usable hosts requires a subnet mask of 255.255.255.252, which allows for 4 IP addresses (2 usable).

To support 500 hosts, a subnet mask of 255.255.254.0 (/23) is required, providing 510 usable addresses.

To accommodate 30 usable addresses, a /27 subnet mask (255.255.255.224) is needed, providing 32 total addresses (30 usable).

To accommodate at least 500 usable addresses, a subnet must have at least 512 total addresses, which corresponds to a /23 subnet mask (255.255.254.0).