Network and Security- Foundations- D315 Exam Questions with Complete Solutions, A+

TCP/IP Transmission Control Protocol/Internet Protocol Application Layer This layer is responsible for the communication protocols between nodes. The protocols in this layer include hypertext transfer protocol (HTTP and HTTPS), Secure Shell (SSH), and network time protocol (NTP), among many others. Transport Layer This layer is responsible for the end-to-end transport of data. The protocols that live in this layer are transmission control protocol (TCP) and user datagram protocol (UDP). Network Layer This layer defines the logical transmission protocols for the whole network. The main protocols that live in this layer are internet protocol (IP), internet control message protocol (ICMP), and address resolution protocol (ARP). Network interface Layer This layer establishes how data should be physically sent through the network. OSI Model Open Systems Interconnection Model Physical Layer (Layer 1) This layer is responsible for the physical connections of the devices in the network. This layer is implemented through the use of devices such as hubs, repeaters, modem devices, and physical cabling. Data Link Layer (Layer 2) This layer is responsible for the error-free delivery of data to the receiving device or node. This layer is implemented through the use of devices such as switches and bridge devices, as well as anything with a network interface, like wireless or wired network cards. Network Layer (Layer 3) This layer is responsible for the transmission of data between hosts in different networks as well as routing of data packets. This layer is implemented through the use of devices such as routers and some switches. Transport layer (layer 4) In this layer protocols ensure that data are transferred from point A to point B reliably and without errors. this layer services include flow control, acknowledgment, error correction, segmentation, reassembly, and sequencing. Session Layer (Layer 5) This layer is responsible for connection establishment, session maintenance, and authentication. Presentation Layer (Layer 6) This layer is responsible for translating data from the application layer into the format required to transmit the data over the network as well as encrypting the data for security if encryption is used. Application Layer (Layer 7) This layer is responsible for network applications (like HTTP or FTP) and their production of data to be transferred over the network. Hub {Physical Layer} -The simplest device used on an Ethernet network for connecting devices to each other -split the bandwidth of a connection among all the computers connected to it - do not perform any packet filtering or addressing functions but instead broadcast data to all computers connected to it Switch {Data and Network Layer} -Provides connectivity to devices in a local network -Creates a dedicated full-speed connection between two computers that are communicating with each other - makes use of the MAC address to deliver the message to the right destination Router{Network Layer} -Interconnect two or more networks -Operate at the border of your network -Stores information about the systems that are connected to it and where to send requests when the destination is unknown -Works at the network layer of the OSI model Wireless Access point {WAP} -Extends a wired network to wireless connections -Involves the IEEE 802.11 group of standards that defines wireless LAN's {WLAN's} -Central connecting point for computers equipped with wireless network adapters - identifies each computer by its MAC address Patch Panel -A box designed as a junction point for twisted pair (TP) cable and fiber cable used in networks. -First step in organizing your cables Firewall -A security hardware appliance or software application that protects a computer or network from unwanted intrusion -Blocks unwanted connections from untrusted networks and can block basic network attacks Modem {Physical and Data link Layer} -Connects a LAN to an internet service provider -Converts digital signals into analog signals and vice versa Network Interface Card (NIC) {Physical Layer} -The interface on a computer or other device that connects to the LAN -Designed to take the communication off the physical cable or wireless signal and present it to the computer for processing -Each NIC has a unique physical address known as a MAC address Bridge {Data link Layer} Connects two or more networks Forwards data to next network with analysis Not widely used in modern networks Repeater{Physical Layer} Amplifies that signal it receives so that it can travel a longer distance