Networks and Security: Quiz 4

The O____ visually organizes network protocols into se_______ layers. Network professionals often use this model to communicate with each other about potential sources of problems or security threats when they occur.

The TCP/IP model combines multiple layers of the OSI model. There are many similarities between the two models. Both models define standards for networking and divide the network communication process into different layers. The TCP/IP model is a sim_________ version of the OSI model.

The first layer is the ? layer that corresponds to the hardware involved in network transmission. Hubs, modems, and the cables and wiring that connect them are all considered part of the layer. To travel across an ethernet or coaxial cable, a data packet needs to be translated into a stream of 0s and 1s. The stream of 0s and 1s are sent across the wiring and cables, received, and then passed on to higher levels of the OSI model.

P

The second is the ? link layer organizes sending and receiving data packets within a single network. The ? link layer is home to switches on the local network and network interface cards on local devices.

Protocols like network control protocol (NCP), high-level data link control (HDLC), and synchronous data link control protocol (SDLC) are used at the ? link layer.

D

The third is the ? layer, which oversees receiving the frames from the data link layer (layer 2) and delivers them to the intended destination. The intended destination can be found based on the address that resides in the frame of the data packets. Data packets allow communication between two networks. These packets include IP addresses that tell routers where to send them. They are routed from the sending to the receiving.

N

The ? layer is responsible for delivering data between devices. This layer also handles the speed of data transfer, flow of the transfer, and breaking data down into smaller segments to make them easier to transport. Segmentation is the process of dividing up a large data transmission into smaller pieces that can be processed by the receiving system. These segments need to be reassembled at their destination so they can be processed at the session layer. The speed and rate of the transmission also has to match the connection speed of the destination system. TCP and UDP are transport layer protocols.

T

A ? describes when a connection is established between two devices. An open ? allows the devices to communicate with each other. ? layer protocols occur to keep the ? open while data is being transferred and terminate the session once the transmission is complete.

The ?layer is also responsible for activities such as authentication, reconnection, and setting checkpoints during a data transfer. If a ? is interrupted, checkpoints ensure that the transmission picks up at the last ? checkpoint when the connection resumes. ? include a request and response between applications. Functions in the ? layer respond to requests for service from processes in the presentation layer and send requests for services to the transport layer.

S

Functions at the ? layer involve data translation and encryption for the network. This layer adds to and replaces data with formats that can be understood by applications on both sending and receiving systems. Formats at the user end may be different from those of the receiving system. Processes at the ? layer require the use of a standardized format.

Some formatting functions that occur at this layer include encryption, compression, and confirmation that the character code set can be interpreted on the receiving system. One example of encryption that takes place at this layer is SSL, which encrypts data between web servers and browsers as part of websites with HTTPS.

P

The ? layer includes processes that directly involve the everyday user. This layer includes all of the networking protocols that software ? use to connect a user to the internet. This characteristic is the identifying feature of the ? layer—user connection to the network via ? and requests.

A