The Open Systems Interconnection Specifications Flashcards
Host 1 sent a SYN packet to Host 2. What will Host 2 send in response?
ACK
NAK
SYN/ACK
SYN/ACK
A connection-oriented session is set up using what is called a three-way handshake. The transmitting host sends a SYN packet, the receiving host sends a SYN/ACK, and the transmitting host replies with the last ACK packet. The session is now set up
TCP and UDP reside at which layer of the OSI model?
2
3
4
4
TCP and UDP are Transport layer protocols. The Transport layer is Layer 4 of the OSI model
Which layer of the OSI model provides an entry point for programs to access the network infrastructure?
Application
Transport
Network
Application
The top layer of the OSI model gives applications access to the services that allow network access
You are connected to a server on the Internet and you click a link on the server and receive a time-out message. What layer could be the source of this message?
Application
Transport
Network
Application
If the remote server is busy or does not respond to your web browser request, this is an Application layer problem
Which layer of the OSI model is responsible for code and character-set conversion as well as recognizing data formats?
Application
Presentation
Session
Presentation
The Presentation layer makes data “presentable” for the Application layer
At which layers of the OSI model do bridges, hubs, and routers primarily operate, respectively?
Physical, Physical, Data Link
Data Link, Data Link, Network
Data Link, Physical, Network
Data Link, Physical, Network
Bridges, like switches, are Data Link layer devices. Hubs, like repeaters, are Physical layer devices. Routers are Network layer devices
Which layer of the OSI model is responsible for converting data into signals appropriate for the transmission medium?
Network
Data Link
Physical
Physical
The Physical layer’s job is to convert data into impulses that are designed for the wired or wireless medium being used on the attached segment
A receiving host has failed to receive all the segments that it should acknowledge. What can the host do to improve the reliability of this communication session?
Send a different source port number.
Decrease the sequence number.
Decrease the window size.
Decrease the window size.
A receiving host can control the transmitter by using flow control (TCP uses windowing by default). By decreasing the window size, the receiving host can slow down the transmitting host so the receiving host does not overflow its buffers
Which Layer 1 devices can be used to enlarge the area covered by a single LAN segment? (Choose two.)
Firewall
NIC
Hub
Repeater
Hub
Repeater
Not that you really want to enlarge a single collision domain, but a hub (multiport repeater) will provide this functionality for you
Segmentation of a data stream happens at which layer of the OSI model?
Data Link
Network
Transport
Transport
The Transport layer receives large data streams from the upper layers and breaks these up into smaller pieces called segments
When data is encapsulated, which is the correct order?
Data, frame, packet, segment, bits
Segment, data, packet, frame, bits
Data, segment, packet, frame, bits
Data, segment, packet, frame, bits
The encapsulation order is data, segment, packet, frame, bits
What are two purposes for segmentation with a bridge? (Choose two.)
To add more broadcast domains
To create more collision domains
To add more bandwidth for users
To allow more broadcasts for users
To create more collision domains
To add more bandwidth for users
Bridges and switches break up collision domains, which allows more bandwidth for users
Acknowledgments, sequencing, and flow control are characteristic of which OSI layer?
Layer 2
Layer 3
Layer 4
Layer 4
A reliable Transport layer connection uses acknowledgments to make sure all data is received reliably. A reliable connection is defined by the use of acknowledgments, sequencing, and flow control, which is characteristic of the Transport layer (Layer 4)
Which of the following is true regarding sequencing and acknowledgments? (Choose all that apply.)
The segments delivered are acknowledged back to the sender upon their reception.
If a segment is not received, the virtual circuit must be restarted from the beginning at a slower transmit interval.
Any segments not acknowledged are retransmitted.
Segments are sequenced back into their proper order upon arrival at their destination.
The segments delivered are acknowledged back to the sender upon their reception.
Any segments not acknowledged are retransmitted.
Segments are sequenced back into their proper order upon arrival at their destination.
When sequencing and acknowledgments are used, the segments delivered are acknowledged back to the sender upon their reception. At this point, any segments not acknowledged are retransmitted, and segments are sequenced back into their proper order upon arrival at their destination
What is the purpose of flow control?
To ensure that data is retransmitted if an acknowledgment is not received
To reassemble segments in the correct order at the destination device
To provide a means for the receiver to govern the amount of data sent by the sender
To provide a means for the receiver to govern the amount of data sent by the sender
Flow control allows the receiving device to control the pace of the transmitting device so the receiving device’s buffer does not overflow
