Model layers and definitions

Question 1

The DoD (TCP/IP) model’s Process/Application Layer does what two main tasks?

Answer 1

1) Defines protocols for node-to-node APPLICATION communication
2) also controls user-interface specs

Question 2

Which layers of the OSI model does the DoD’s Process/Application layer correspond to?

Answer 2

Application, Presentation and Session layers

Question 3

The DoD’s Host to Host layer performs what function?

Answer 3

1) It defines protocols for setting up reliable end-to-end communication
2) Ensures error-free delivery of data

Question 4

Which DoD and OSI layer handles packet sequencing and maintains data integrity?

Answer 4

Host-to-Host / Transport layer

Question 5

Which layer handles logical transmission of packets over the entire network and gives hosts IP addresses?

Answer 5

Internet / Network layer

Question 6

Which DoD layer is associated with hardware addressing and defines protocols for physical transmission of data? What is it’s OSI equivalent?

Answer 6

Network Access Layer. It’s equivalent is the Data Link and Physical layer

Question 7

Name the two major groups of OSI layers and their functions

Answer 7

1) Upper Layers (Application Presentation and Session). Define how applications communicate with each other
2) Lower Layers (Transport,Network,Data Link,Physical). Define how the application data reaches it’s destination.

Question 8

A PDU at the Transport Layer is known as what?

Answer 8

Segment (TCP) or Datagram (UDP)

Question 9

Flow Control is done at what TCP/IP layer?

Answer 9

Host-to-Host layer (Transport)

Question 10

The Window size sets the amount of what a sending host can send before it has to wait for an acknowledgement?

Answer 10

Bytes. Not Segments.

Question 11

Name 4 devices that work at all 7-layers of the OSI model

Answer 11

1) Network Management stations
2) web and application servers
3) Gateways (not default)
4) Network Hosts

Question 12

Name 4 devices that operate primarily at the Physical layer

Answer 12

1) NICs
2) Transceivers
3) Repeaters
4) Hubs

Question 13

What other layer can provide flow control and error management?

Answer 13

The LLC sub-layer, but this is optional and only applies to control between nodes on the same physical link.

Question 14

What layer is responsible for identifying network protocols, encapsulating and multiplexing them?

Answer 14

LLC sub-layer of Datalink layer

Question 15

Which IEEE standard defines the LLC sub-layer?

Answer 15

802.2

Question 16

What does 802.3 define and what LAN access method?

Answer 16

Ethernet. The access method is CSMA/CD.

Question 17

A datagram is the term used for what two things?

Answer 17

1) The PDU of the Transport Layer when UDP is used (segments when it’s TCP)
2) Used to describe IP data transfer, i.e. an IP Datagram

Question 18

A packet can encapsulate what two types of PDU’s?

Answer 18

Segments and Datagrams

Question 19

What protocol uses a Maximum Segment Size and what does it define?

Answer 19

TCP. It defines how much data from the upper layers is contained in a Segment.

Question 20

If Maximum Segment Size defines the size of TCP segments, what defines the size of UDP datagrams?

Answer 20

The length field in the IP header. (I don’t think this is covered in exam but is a useful comparison with the MSS)

Question 21

At which layer would application programmers specify how applications communicate to each other over the network?

Answer 21

Session layer. (Simplex, Half-duplex and full duplex communication)

Question 22

List the correct order of events during the 3-way handshake of establishing a reliable connection?

Answer 22

1) SYN
2) SYN/ACK
3) ACK

Question 23

Which layers of the OSI model do not have protocols in the TCP/IP suite exclusively dedicated to them?

Answer 23

Session layer and Presentation layer
(the functions of the session layer are primarily implemented in the transport layer protocols TCP and UD) *this was in the Comptia practice tests publication. I have no idea what it means and cannot find out anywhere what functions it is talking about.