3.8.2 Module Quiz – Protocols and Models (Answers)

Explanation: Decoding is the process of receiving transmitted data and reversing the encoding process to interpret the information. An example is a person that listens to a voicemail and decodes the sounds to understand the received message.

Explanation: When messages are sent on a network, the encapsulation process works from the top of the OSI or TCP/IP model to the bottom. At each layer of the model, the upper layer information is encapsulated into the data field of the next protocol. For example, before an IP packet can be sent, it is encapsulated in a data link frame at Layer 2 so that it can be sent over the physical medium.

Explanation: Encapsulation is the process of placing one message format into another message format. An example is how a packet is placed in its entirety into the data field as it is encapsulated into a frame.

Explanation:
1. HTTP governs the way that a web server and client interact.
2. TCP manages individual conversations between web servers and clients.
3. IP is responsible for delivery across the best path to the destination.
4. Ethernet takes the packet from IP and formats it for transmission.

Explanation: Some vendors have developed their own reference models and protocols. Today, if a device is to communicate on the Internet, the device must use the TCP/IP model. The benefits of using a layered model are as follows:

• assists in protocol design
• fosters competition between vendors
• prevents a technology that functions at one layer from affecting any other layer
• provides a common language for describing network functionality
• helps in visualizing the interaction between each layer and protocols between each layer

Explanation: Protocols provide rules that define how a message is transmitted across a network. Implementation requirements such as electronic and bandwidth details for data communication are specified by standards. Operating systems are not specified by protocols, but will implement protocols. Protocols determine how and when to send a message but they do not control the contents of a message.

Explanation: The destination IP address is used for end-to-end delivery of data to a remote network. The destination MAC address is used for delivery on a local network. The destination port number identifies the application that should process the data at the destination. Source addresses identify the sender of the data.

Explanation: The term protocol data unit (PDU) is used to describe a piece of data at any layer of a networking model. A packet is the PDU at the network layer. A frame is the data link layer PDU. A segment is the PDU at the transport layer.

Explanation: ICMP and IP both function at the internet layer, whereas PPP is a network access layer protocol, and POP and BOOTP are application layer protocols.

Explanation: The OSI model consists of seven layers: application, presentation, session, transport, network, data link, and physical. The transport layer defines services to segment, transfer, and reassemble the data for individual communications between the end devices.

Explanation: Multicast is a one-to-many communication where the message is delivered to a specific group of hosts. Broadcast communication is a one-to-all communication. A unicast communication is a one-to-one communication. Anycast is an IPv6 term and is the sending of data in a one-to-nearest communication.

Explanation: TCP/IP is a protocol stack that contains a lot of other protocols such as HTTP, FTP, and DNS. The TCP/IP protocol stack is required to be used when communicating on the Internet. A MAC address is an address that is burned into an Ethernet network card. OSI is the 7 layer model that is used to explain how networking works.

Explanation: Broadcast communication is a one-to-all communication. A unicast communication is a one-to-one communication. Multicast is a one-to-many communication where the message is delivered to a specific group of hosts. Allcast is not a standard term to describe message delivery.

Explanation: Before a message is sent across a network it must first be encoded. Encoding is the process of converting the data message into another format suitable for transmission across the physical medium. Each bit of the message is encoded into a pattern of sounds, light waves, or electrical impulses depending on the network media over which the bits are transmitted. The destination host receives and decodes the signals in order to interpret the message.

Explanation: When all devices need to receive the same message simultaneously, the message would be delivered as a broadcast. Unicast delivery occurs when one source host sends a message to one destination host. The sending of the same message from a host to a group of destination hosts is multicast delivery. Duplex communications refers to the ability of the medium to carry messages in both directions.