Which of the following correctly describe steps in the OSI data encapsulation process? (Choose two)
A.
The transport layer divides a data stream into segments and may add reliability and flow control information.
B.
The data link layer adds physical source and destination addresses and an FCS to the segment.
C.
Packets are created when the network layer encapsulates a frame with source and destination host addresses and protocol-related control information.
D.
Packets are created when the network layer adds Layer 3 addresses and control information to a segment.
E.
The presentation layer translates bits into voltages for transmission across the physical link.
Explanation:
he Application Layer (Layer 7) refers to communications services to applications and is the interface between the network and the application. Examples include: Telnet, HTTP, FTP, Internet browsers, NFS, SMTP gateways, SNMP, X.400 mail, and FTAM.The Presentation Layer (Layer 6) defining data formats, such as ASCII text, EBCDIC text, binary, BCD, and JPEG. Encryption also is defined as a presentation layer seivice. Examples include: JPEG, ASCII. EBCDIC, TIFF, GIF, PICT, encivption, MPEG, and MIDI.
The Session Layer (Layer 5) defines howto start, control, and end communication sessions. This includes the control and management of multiple bidirectional messages so that the application can be notified if only some of a series of messages are completed. This allows the presentation layer to have a seamless view of an incoming stream of data. The presentation layer can be presented with data if all flows occur in some cases. Examples include: RPC, SQL, NFS, NetBios names, AppleTalk ASP, and DECnet SCP
The Transport Layer (Layer 4) defines several functions, including the choice of protocols. The most important Layer 4 functions are error recovery and flow control. The transport layer may provide for retransmission, i .e., error recovery, and may use flow control to prevent unnecessary congestion by attempting to send data at a rate that the network can accommodate, or it might not, depending on the choice of protocols. Multiplexing of incoming data for different flows to applications on the same host is also performed. Reordering of the incoming data stream when packets arrive out of order is included. Examples include: TCP, UDP, and SPX.
The Network Layer (Layer 3) defines end-to-end delivery of packets and defines logical addressing to accomplish this. It also defines how routing works and how routes are learned; and howto fragment a packet into smaller packets to accommodate media with smaller maximum transmission unit sizes. Examples include: IP, IPX, AppleTalk DDP, and ICMP. Both IP and IPX define logical addressing, routing, the learning of routing information, and end-to-end deliver/ rules. The IP and IPX protocols most closely match the