ccna question 2019

ccna question 2019.The transport layer establishes and maintains session layer connections and provides reliable and unreliable data transmission, traffic control, and multiplexing of connections. A handshake process is typically required to establish a reliable connection; acknowledgement is used to provide reliable transmission. Port numbers or socket numbers are used for multiplexing of connections. Ready/not-ready signaling and windowing techniques are used to implement traffic control; however, windowing techniques are more efficient than ready/not-ready signaling.The network layer defines the logical address, determines the path to the destination based on the network portion of the address, and connects the different types of Layer 2 media. Routers are used to limit the propagation of broadcasts; routers use a routing table containing a list of destination network numbers to help find destinations; if a destination is not found in the routing table, traffic to that destination is discarded.The data link layer defines hardware addresses. the MAC address is 48 bits long and is expressed in hexadecimal; the first 24 bits (the first 6 hex bits) are OUI. the MAC address must be unique within the same logical network segment. Unicast frames are sent to all devices in the segment, but only one device will process it; multicast frames are sent to a group of devices; and broadcast frames are sent to all devices.PDUs describe the data and its overhead. Application layer PDUs are referred to as data, network layer PDUs are referred to as packets or datagrams, data link layer PDUs are referred to as frames, and physical layer PDUs are referred to as bits. As traffic passes down the protocol stack, each layer encapsulates the PDUs of the previous layer, and the unencapsulation process will be performed at the destination.2-5 Two-Minute Sprint.Introduction to the OSI Reference Model .The OSI reference model provides the following benefits: improves interoperability, defines how to connect adjacent layers, supports component separation, supports modular design, can be used as a teaching tool, and simplifies troubleshooting.Layers of the OSI Reference Model . The application layer (layer 7) provides the user interface; the representation layer (layer 6) defines how information is presented to the user; the session layer (layer 5) determines whether a network connection is needed and initiates the process of connection establishment and removal; the transport layer (layer 4) handles the reliable and unreliablereliable service mechanisms; the network layer (layer 3) creates the logical topology using logical addresses, and routers run at this layer; the data link layer (layer 2) assigns physical (MAC) addresses and defines how devices communicate over specific media types, and bridges, switches, and NICs all run at this layer; and the physical layer (layer 1) handles all the physical characteristics of connections, and hubs and transponders all run at this layer.. The data link layer defines the MAC address, the physical (hardware) topology, and the framing method; it also provides connection-oriented and connectionless services. 48 bits long, the MAC address is expressed in hexadecimal, with the first 6 bits being the OUI (vendor code), and the last 6 bits being the NIC number. Unicast is sent to one target device in the segment, multicast is sent to a group of devices , and broadcast (FF:FF:FF:FF:FF:FF:FF) is sent to all devices.. The network layer defines the logical address, determines the path to the destination based on the network number in the logical address, and connects the different types of media. The router then runs at the network layer. The routing table contains the destination network numbers and information about how to get to those networks. Routers restrict the propagation of broadcasts, provide scalability through a hierarchical design, make better decisions about getting to destinations than bridges, can use VLANs to exchange datagrams on the same interface, and are capable of advanced features such as QoS and filtering.