The picture below shows the comparison between TCP/IP model & OSI model. The Internet Layer of TCP/IP is equivalent to the Network Layer which is responsible for routing decision.
Refer to the exhibit. A network administrator cannot establish a Telnet session with the indicated router. What is the cause of this failure?
A. A Level 5 password is not set.
B. An ACL is blocking Telnet access.
C. The vty password is missing.
D. The console password is missing.
Telnet is a protocol that enables you to connect to remote computers and local computers over a TCP/IP network, over TCP port 23.
The VTY lines are the Virtual Terminal lines of the router, used solely to control inbound Telnet connections. They are virtual, in the sense that they are a function of software – there is no hardware associated with them. They appear in the configuration as line vty 0 4.
Each of these types of lines can be configured with password protection. Lines can be configured to use one password for all users, or for user-specific passwords. User-specific passwords can be configured locally on the router, or you can use an authentication server to provide authentication.
Before installing a new, upgraded version of the IOS, what should be checked on the router, and which command should be used to gather this information? (Choose two)
A. the amount of available ROM
B. the amount of available flash and RAM memory
C. the version of the bootstrap software present on the router
D. show version
E. show processes
F. show running-config
Answer: B D
Before you begin the upgrade of router new version of the IOS you need to check if there is enough memory and RAM before copying the IOS to the Flash.
You can check both with the “show version” command.
Refer to the exhibit. An administrator pings the default gateway at 10.10.10.1 and sees the output as shown. At which OSI layer is the problem?
A. data link layer
B. application layer
C. access layer
D. session layer
E. network layer
The problem resonates at the network layer which is responsible for network addressing and routing through the internetwork.
At which layer of the OSI model does PPP perform?
A. Layer 2
B. Layer 3
C. Layer 4
D. Layer 5
PPP operates as a data link layer protocol of the OSI provides a single, pre-established WAN communications path from the customer premises through a carrier network, such as a telephone company, to a remote network.
Layer 2 is the data link where data packets are encoded and decoded into bits.
The MAC (Media Access Control) sub layer controls how a computer on the network gains access to the data and permission to transmit it and the LLC (Logical Link control) layer controls frame synchronization, flow control and error checking.
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.
Answer: A D
(A) The Transport Layer segments data into smaller pieces for transport. Each segment is assigned a sequence number, so that the receiving device can reassemble the data on arrival.
The Transport Layer also uses flow control to maximize the transfer rate while minimizing the requirements to retransmit. For example, in TCP, basic flow control is implemented by acknowledgment by the receiver of the receipt of data; the sender waits for this acknowledgment before sending the next part.
(D) The Network Layer (Layer 3) has two key responsibilities. First, this layer controls the logical addressing of devices. Second, the network layer determines the best path to a particular destination network, and routes the data appropriately.
A network administrator is verifying the configuration of a newly installed host by establishing an FTP connection to a remote server. What is the highest layer of the protocol stack that the network administrator is using for this operation?
F. data link
FTP belongs to Application layer and it is also the highest layer of the OSI model.
At which layer of the OSI model is RSTP used to prevent loops?
A. data link
Which layer in the OSI reference model is responsible for determining the availability of the receiving program and checking to see if enough resources exist for that communication?
A receiving host computes the checksum on a frame and determines that the frame is damaged. The frame is then discarded. At which OSI layer did this happen?
D. data link
The term “frame” is in relation to the Data Link layer. In this layer, an Frame Check Sequence (FCS) field is added to the frame to verify that the frame data is received correctly.