Encapsulation wraps data with the necessary protocol information
What is a network?
·
A network is a
collection of devices and end systems.
What four major
categories make up the physical components of a network?
·
Endpoints: These
devices receive data and are endpoints of the network. Examples include PCs,
servers, laptops, tablets, and so on.
Interconnections: The components that provide a means for data to travel across
the network. This includes network interface cards (NIC), network media, and
connectors.
Switches: Provide network access for compute devices and other network devices.
Image Routers: Interconnect networks.
What are the four
major resources that are shared on a computer network?
·
Data and applications:
Consist of computer data and network-aware applications such as e-mail
Resources: Include input and output devices such as cameras and printers
Network storage: Consists of directly attached storage devices (physical
storage that is directly attached to a computer and a shared server), network
attached storage, and storage-area networks
Backup devices: Can back up files and data from multiple computers
What are common
network user applications on today's networks?
·
Common network user
applications on today's networks are
Email
Web (this includes web applications or any application the uses HTTP/HTTPS)
Instant messaging
Video/collaboration
Databases
File sharing
List three categories
of network applications.
·
Batch applications:
Examples are FTP and TFTP. They are started by a person and complete with no
other interaction. Bandwidth is important but not critical.
Interactive applications: Include database updates and queries. A person
requests data from a server and waits for a reply. Response time depends more
on the server and storage than the network.
Real-time applications: Include VoIP and video. Network bandwidth is critical
because these applications are time sensitive. Quality of service (QoS) and
sufficient network bandwidth are mandatory for these applications.
What are three types
of network-monitoring software?
·
Protocol analyzers:
Capture network packets between network devices and decode the packets so that
one can view what applications are being transmitted on a network.
Sniffers: Work like a wiretap and allow one to observe network communication
and view the data that is being transmitted.
Availability and performance programs: Use protocols use as ICMP and SNMP to
view the availability of network devices and performance in real time.
Your company wants to
provide streaming video services to all branches and sales representatives.
What two network characteristics are the most critical to achieving this goal?
·
The most critical
characteristics are bandwidth and latency.
Time-sensitive applications such as video and VoIP are dependent on bandwidth
and latency to function properly. When implementing time-sensitive
applications, one needs to ensure that the network has enough bandwidth and low
delay to ensure a proper end-user experience.
When describing the
characteristics of a network, what does speed refer to?
·
Speed refers to how
fast data is transmitted over the network.
Today's networks consist of speeds of 100 Mbps, 1Gbps, 10 Gbps, 40 Gbps, and
100 Gbps.
When describing the
characteristics of a network, what does cost refer to?
·
Cost refers to the
general financial value of network components, installation, and maintenance.
When describing the
characteristics of a network, what does security refer to?
·
Security refers to
protecting the network devices and data from both internal and external
sources.
When describing the
characteristics of a network, what does availability refer to?
·
Availability is the
measurement of the network uptime compared to its downtime.
Your CIO wants to know
the network availability of your company's network for the past year. During
the past year, the network was down for 30 minutes. What was the total
availability of the network?
·
The total availability
was 99.994%.
When describing the
characteristics of a network, what does scalability refer to?
·
Scalability refers to
how well the network can accommodate more users and more data—in other words,
how easily the network can grow and expand.
When describing the
characteristics of a network, what does reliability refer to?
·
Reliability refers to
the dependability of the devices that make up the network (switches, routers,
computers, servers, access points, software, and so on).
What is the difference
between the physical and logical network topology?
·
Physical topology
defines the physical layout of devices and network media—cables, network
devices, computers, and so on—and how these components are physically connected
and configured.
Logical topology refers to the data path or logical paths of the network in
which data accesses the media and transmits packets across it. This includes IP
addresses as well as routing paths.
What are the six types
of physical topologies implemented in today's networks?
·
Star,Extended
star,Mesh,Partial mesh, Bus,Ring
What physical network
topology connects all devices to one cable?
·
The bus topology connects
all devices to one cable.
Describe a ring
physical network topology.
·
Single-ring: In a
single-ring network, all devices share a single cable and data travels in one
direction. Each device waits its turn to send data over the network.
Dual-ring: A dual-ring network has a second ring to add redundancy and allows
data to be sent in both directions.
Describe a star and
extended star physical topology.
·
Star and extended star
physical topologies are made up of a central connection point, such as a hub or
switch, where all cable segments connect. A star topology resembles spokes in a
bicycle wheel and is the network topology of choice in Ethernet networks.
When multiple star topologies are connected to a common independent centralized
device, it is called an extended star topology.
What physical network
topology connects all devices to each other?
·
A mesh network
topology connects all devices to each other for fault tolerance and redundancy.
What is the difference
between a full-mesh and a partial-mesh topology?
·
A full-mesh topology
connects all nodes to one another for full redundancy. In a partial-mesh
topology, at least one node maintains multiple connections to all other devices
and one node cannot connect to all other nodes as well.
What are the seven
layers of the OSI reference model? Include the layer number and name of each
layer in your answer.
·
The seven layers of
the OSI reference model are as follows:
Layer 7: Application layer
Layer 6: Presentation layer
Layer 5: Session layer
Layer 4: Transport layer
Layer 3: Network layer
Layer 2: Data link layer
Layer 1: Physical layer
What is the function
of the physical layer (Layer 1) in the OSI model? Give some examples of
physical layer implementation.
·
The physical layer
defines the physical medium. It defines the media type, the connector type, and
the signaling type (baseband versus broadband). This includes voltage levels,
physical data rates, and maximum cable lengths. The physical layer is
responsible for converting frames into electronic bits of data, which are then
sent or received across the physical medium. Twisted-pair, coaxial, and
fiber-optic cable operate at this level. Other implementations at this layer
are repeaters/hubs.
What is the
responsibility of the data link layer (Layer 2)?
·
e data link layer
defines how data is formatted from transmission and how access to the physical
media is controlled. This layer also typically includes error correction to
ensure reliable delivery of data.
The data link layer translates messages from the network layer into bits for
the physical layer, and it enables the network layer to control the
interconnection of data circuits within the physical layer. Its specifications
define different network and protocol characteristics, including physical addressing,
error notification, network topology, and sequencing of frames.
Data-link protocols provide the delivery across individual links and are
concerned with the different media types, such 802.3. The data link layer is
responsible for putting 1s and 0s into a logical group. These 1s and 0s are
then put on the physical wire. Some examples of data link layer implementations
are IEEE 802.3, packet trailer (for Ethernet, frame check sequence [FCS] or
cyclic redundancy check [CRC]), Fiber Distributed Data Interface (FDDI),
High-Level Data Link Control (HDLC), and Frame Relay
The Institute of
Electrical and Electronics Engineers (IEEE) defines what sublayer of the data
link layer?
·
The IEEE defines the
Media Access Control (MAC) sublayer of the data link layer.
What functions does
the Media Access Control (MAC) sublayer provide?
·
The MAC sublayer
specifies how data is placed and transported over the physical wire. It
controls access to the physical medium.
The MAC sublayer communicates downward directly to the physical layer. Physical
addressing (MAC addresses), network topologies, error notification, and
delivery of frames are defined at the MAC sublayer.
What are examples of
network devices that operate at the data link layer (Layer 2)?
·
Bridges and switches
operate at the data link layer.
Both devices make decisions about what traffic to forward or drop (filter) by
MAC addresses; logical network address are not used at this layer. Data link
layer devices assume a flat address space.
Describe the function
of the network layer (Layer 3) of the OSI model. Give some examples of network
layer implementations.
·
The network layer
provides internetwork routing and logical network addresses. It defines how to
transport traffic between devices that are not locally attached.
The network layer also supports connection-oriented and connectionless service
from higher-layer protocols.
Routers and multilayer switches operate at the network layer. IP and IPv6 are
examples of network layer implementations.
Are network layer
addresses physical or logical?
·
Network layer
addresses are logical.
These addresses are logical addresses that are specific to the network layer
protocol being run on the network. Each network layer protocol has a different
addressing scheme. They are usually hierarchical and define networks first and
then hosts or devices on that network. An administrator typically assigns
network layer addresses either by static configuration or dynamic
configuration.
An example of a network address is an IP address. For example, IPv4 has 32-bit
addresses often expressed in decimal format. An example of an IPv4 address in
decimal format is 192.168.0.1.
What is the transport
layer (Layer 4) of the OSI model responsible for? Give some examples of transport
layer implementations.
·
The transport layer
segments and reassembles data from upper-layer applications into data streams.
It provides reliable data transmission to upper layers.
End-to-end communications, flow control, multiplexing, error detection and
correction, and virtual circuit management are typical transport layer
functions. Some examples include Transmission Control Protocol (TCP) and User
Datagram Protocol (UDP).
What layer of the OSI
model handles the reliability of network communications between hosts using
flow control, sequencing, and acknowledgments?
·
The transport layer
handles this reliability.
The transport layer uses acknowledgments and sequence numbers for reliable
delivery of data. Flow control is used to avoid network or host congestion.
What is flow control,
and what are the three methods of implementing it?
·
Flow control is the
method of controlling the rate at which a computer sends data, thus preventing
network congestion.
The three methods of implementing flow control are as follows:
Buffering
Congestion avoidance
Windowing
How do network devices
use buffering for flow control?
·
Buffering is used by
network devices to temporarily store bursts of extra data in memory until they
can be processed and sent. Buffering can handle occasional data bursts;
however, buffer overflows can occur if data bursts are continuous.
What are the functions
of the session layer (Layer 5) of the OSI model? Provide some examples.
·
The session layer is
responsible for creating, managing, and ending communication sessions between
presentation layer entities.
These sessions consist of service requests and responses that develop between
applications located on different network devices. Some examples include
Structured Query Language (SQL), remote-procedure call (RPC), and SSL.
What is the
responsibility of the presentation layer (Layer 6)? Give some examples of Layer
6 implementations.
·
Also known as the
translator, the presentation layer provides coding and conversion functions to
application layer data. This guarantees that the application layer on one
system can read data transferred from the application layer of a different
system. Some examples of the presentation layer are
Compression, decompression, and encryption
JPEG, TIFF, GIF, PICT, QuickTime, MPEG, EBCDIC, and ASCII file types
What does the
application layer (Layer 7) of the OSI model do, and what are some examples of
this layer?
·
The application layer
is the layer that is closest to the user. This means that this layer interacts
directly with the software application. The application layer's main functions
are to identify and establish communication partners, determine resource
availability, and synchronize communication. Some examples include TCP/IP
applications protocols such as Telnet, FTP, Simple Mail Transfer Protocol
(SMTP), and HTTP.
How do the different
layers of the OSI model communicate with each other?
·
Each layer of the OSI
model can communicate only with the layer above it, below it, and parallel to
it (a peer layer on a remote host).
For example, the presentation layer can communicate with only the application
layer and session layer on the local host, and the presentation layer on the
remote host. These layers communicate with each other using service access
points (SAP) and protocol data units (PDU). The SAP is a conceptual location at
which one OSI layer can request the services of another OSI layer. PDUs control
information that is added to the user data at each layer of the model. This
information resides in fields called headers (the front of the data field) and
trailers (the end of the data field).
Which layer of the OSI
model uses the hardware address of a device to ensure proper message delivery
to a host on a LAN?
·
The data link layer
uses physical addresses or hardware addresses for message delivery on a LAN.
Which network layer
protocols are responsible for path determination and traffic switching?
·
Routing protocols are
responsible for path determination and traffic switching.
At which layer on the
OSI model is a logical path created between two host systems?
·
The network layer
creates a logical path between two host systems.
The logical path consists of logical addresses. Logical addresses are also
known as network layer addresses.
At which layers of the
OSI model do WANs operate?
·
WANs operate at the
data link and physical layers.
The physical and data link layers work together to deliver data across a
variety of types of physical networks like LANs, MANs, and WANs.
What are the four
layers of the TCP/IP stack?
·
he four layers of the
TCP/IP stack are as follows:
Application
Transport
Internet
Network Access
On what layer are
physical data rates, connectors, and MAC addresses located in the TCP/IP stack?
·
Physical data rates,
connectors, and MAC addresses are located on the network access layer.
What are some
protocols that operate at the TCP/IP Internet layer?
·
Some protocols that
operate at the TCP/IP Internet layer are as follows:
IP
ICMP (Internet Control Message Protocol)
ARP (Address Resolution Protocol)
RARP (Reverse Address Resolution Protocol)
IP is the main connectionless routed protocol at the Internet layer (or OSI
network layer). IP has various associated protocols, such as ICMP, ARP, and
RARP.
What is the process
that data goes through when a host transmits data across a network to another
host?
·
This process is known
as encapsulation.
Encapsulation wraps data with the necessary protocol information before network
transmission. For data to be transferred to other hosts on a network, it is
encapsulated into a PDU.
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