MODULO1-3 Flashcards
peer-to-peer
Client and server software usually run on separate computers, but it is also possible for one
computer to be used for both roles at the same time. In small businesses and homes, many
computers function as the servers and clients on the network. This type of network is called
a peer-to-peer network.
end device initiates communication
When an end device initiates communication, it uses the address of the destination end
device to specify where to deliver the message.
Intermediary devices
Intermediary devices connect the individual end devices to the network. They can connect
multiple individual networks to form an internetwork. These intermediary devices provide
connectivity and ensure that data flows across the network.
Intermediary devices use the destination end device address, in conjunction with
information about the network interconnections, to determine the path that messages
should take through the network.
Communication
Communication transmits across a network on media. The media provides the channel
over which the message travels from source to destination.
types of media to interconnect devices
Metal wires within cables - Data is encoded into electrical impulses.
* Glass or plastic fibers within cables (fiber-optic cable) - Data is encoded into
pulses of light.
* Wireless transmission - Data is encoded via modulation of specific frequencies of
electromagnetic waves.
, specialized terminology is used to describe how each
of these devices and media connect to each other:
Network Interface Card (NIC) - A NIC physically connects the end device to the
network.
* Physical Port - A connector or outlet on a networking device where the media
connects to an end device or another networking device.
* Interface - Specialized ports on a networking device that connect to individual
networks. Because routers connect networks, the ports on a router are referred to
as network interfaces.
Physical topology
diagrams illustrate the physical location of intermediary devices and
cable installation.
Logical topology
diagrams illustrate devices, ports, and the addressing scheme of the
network.
Intranet
is a term often used to refer to a private connection of LANs and WANs that
belongs to an organization. An intranet is designed to be accessible only by the
organization’s members, employees, or others with authorization.
extranet
An organization may use an extranet to provide secure and safe access to individuals who
work for a different organization but require access to the organization’s data. Here are
some examples of extranets:
* A company that is providing access to outside suppliers and contractors
* A hospital that is providing a booking system to doctors so they can make
appointments for their patients
* A local office of education that is providing budget and personnel information to the
schools in its district
Cable
Typically offered by cable television service providers, the internet data
signal transmits on the same cable that delivers cable television. It provides a high
bandwidth, high availability, and an always-on connection to the internet.
DSL
Digital Subscriber Lines also provide high bandwidth, high availability, and an
always-on connection to the internet. DSL runs over a telephone line. In general,
small office and home office users connect using Asymmetrical DSL (ADSL), which
means that the download speed is faster than the upload speed.
Cellular
Cellular internet access uses a cell phone network to connect. Wherever
you can get a cellular signal, you can get cellular internet access. Performance is
limited by the capabilities of the phone and the cell tower to which it is connected.
Satellite
The availability of satellite internet access is a benefit in those areas that
would otherwise have no internet connectivity at all. Satellite dishes require a clear
line of sight to the satellite.
Dial-up Telephone
An inexpensive option that uses any phone line and a
modem. The low bandwidth provided by a dial-up modem connection is not
sufficient for large data transfer, although it is useful for mobile access while
traveling.
four basic characteristics that network
architects must address to meet user expectations:
Fault Tolerance
* Scalability
* Quality of Service (QoS)
* Security
A fault tolerant
is one that limits the number of affected devices during a failure. It
is built to allow quick recovery when such a failure occurs. These networks depend on
multiple paths between the source and destination of a message. If one path fails, the
messages are instantly sent over a different link. Having multiple paths to a destination is
known as redundancy.
A scalable
expands quickly to support new users and applications. It does this
without degrading the performance of services that are being accessed by existing users.
The figure shows how a new network is easily added to an existing network. These
networks are scalable because the designers follow accepted standards and protocols.
Quality of Service (QoS)
is an increasing requirement of networks today. New applications
available to users over networks, such as voice and live video transmissions, create higher
expectations for the quality of the delivered services. Have you ever tried to watch a video
with constant breaks and pauses? As data, voice, and video content continue to converge
onto the same network, QoS becomes a primary mechanism for managing congestion and
ensuring reliable delivery of content to all users.
Congestion occurs when the demand for bandwidth exceeds the amount available.
Network administrators must address two types
of network security concerns:
network infrastructure security and information security.
Securing the network infrastructure
includes physically securing devices that provide
network connectivity and preventing unauthorized access to the management software that
resides on them, as shown in the figure.
Network administrators must also protect the information contained within the packets
being transmitted over the network, and the information stored on network attached
devices. In order to achieve the goals of network security, there are three primary
requirements.
Confidentiality - Data confidentiality means that only the intended and authorized
recipients can access and read data.
* Integrity - Data integrity assures users that the information has not been altered in
transmission, from origin to destination.
* Availability - Data availability assures users of timely and reliable access to data
services for authorized users.
As new technologies and end-user devices come to market, businesses and consumers
must continue to adjust to this ever-changing environment. There are several networking
trends that affect organizations and consumers:
Bring Your Own Device (BYOD)
* Online collaboration
* Video communications
* Cloud Computing
Bring Your Own Device (BYOD).
The concept of any device, for any content, in any manner, is a major global trend that
requires significant changes to the way we use devices and safely connect them to
networks. This is called Bring Your Own Device (BYOD).
BYOD enables end users the freedom to use personal tools to access information and
communicate across a business or campus network.
ONLINE COLLABORATION
Individuals want to connect to the network, not only for access
to data applications, but also to collaborate with one another. Collaboration is defined as
“the act of working with another or others on a joint project.” Collaboration tools, like Cisco
WebEx, shown in the figure, give employees, students, teachers, customers, and partners
a way to instantly connect, interact, and achieve their objectives.
VIDEO COMMUNICATIONS
Another facet of networking that is critical to the
communication and collaboration effort is video. Video is used for communications,
collaboration, and entertainment. Video calls are made to and from anyone with an internet
connection, regardless of where they are located.
Cloud computing
is one of the ways that we access and store data. Cloud computing allows
us to store personal files, even backup an entire drive on servers over the internet.
Applications such as word processing and photo editing can be accessed using the cloud.
For businesses, Cloud computing extends the capabilities of IT without requiring
investment in new infrastructure, training new personnel, or licensing new software. These
services are available on-demand and delivered economically to any device that is
anywhere in the world without compromising security or function.
Powerline
networking for home networks uses existing electrical wiring to connect devices,.
Using a standard powerline adapter, devices can connect to the LAN wherever there is an
electrical outlet. No data cables need to be installed, and there is little to no additional
electricity used.
Wireless Internet Service Provider (WISP)
is an ISP that connects subscribers to a
designated access point or hot spot using similar wireless technologies found in home
wireless local area networks (WLANs). WISPs are more commonly found in rural
environments where DSL or cable services are not available.
WIRELESS BROADBAND
This solution uses the same cellular technology as a smart
phone.
Viruses, worms, and Trojan horses
These contain malicious software or code
running on a user device.
Spyware and adware
These are types of software which are installed on a user’s
device. The software then secretly collects information about the user.
Zero-day attacks
Also called zero-hour attacks, these occur on the first day that a
vulnerability becomes known.
Threat actor attacks
A malicious person attacks user devices or network
resources.
Denial of service attacks
These attacks slow or crash applications and
processes on a network device.
Data interception and theft
This attack captures private information from an
organization’s network.
Identity theft
This attack steals the login credentials of a user in order to access
private data.
These are the basic security components for a home or small office network:
Antivirus and antispyware - These applications help to protect end devices from
becoming infected with malicious software.
* Firewall filtering - Firewall filtering blocks unauthorized access into and out of the
network. This may include a host-based firewall system that prevents unauthorized
access to the end device, or a basic filtering service on the home router to prevent
unauthorized access from the outside world into the network.
Larger networks and corporate networks use antivirus, antispyware, and firewall filtering,
but they also have other security requirements:
Dedicated firewall systems - These provide more advanced firewall capabilities
that can filter large amounts of traffic with more granularity.
* Access control lists (ACL) - These further filter access and traffic forwarding
based on IP addresses and applications.
* Intrusion prevention systems (IPS) - These identify fast-spreading threats, such
as zero-day or zero-hour attacks.
* Virtual private networks (VPN) - These provide secure access into an
organization for remote workers.
internet
The internet is a network of networks that connects hundreds of millions of computers
world-wide.
LAN i
A LAN is a network infrastructure that spans a small geographical area. A WAN is a network
infrastructure that spans a wide geographical area.
Intranet
refers to a private connection of LANs and WANs that belongs to an organization.
extranet
An organization may use an extranet to provide secure and safe access to individuals who
work for a different organization but require access to the organization’s data.
SOHO i
internet connections include cable, DSL, Cellular, Satellite, and Dial-up telephone.
Business internet connections include Dedicated Leased Line, Metro Ethernet, Business
DSL, and Satellite.
Console
This is a physical management port that provides out-of-band access to a Cisco
device. Out-of-band access refers to access via a dedicated management channel that is
used for device maintenance purposes only. The advantage of using a console port is that
the device is accessible even if no networking services are configured, such as performing
the initial configuration.
Secure Shell (SSH)
SSH is an in-band and recommended method for remotely esta -
blishing a secure CLI connection, through a virtual interface, over a network.
Telnet
Telnet is an insecure, in-band method of remotely establishing a CLI session,
through a virtual interface, over a network.
shell and a kernel.
The kernel interacts with
the hardware and the shell interfaces between the kernel and the users.
auxiliary
Some devices, such as routers, may also support a legacy auxiliary port that was
used to establish a CLI session remotely over a telephone connection using a modem.
Similar to a console connection, the AUX port is out-of-band and does not require
networking services to be configured or available.
