Ch1 Explore the Network - John Flashcards
1
Q
Peer-to-Peer (P2P) File Sharing
A
Peer-to-Peer file sharing allows people to share files with each other without having to store and download them from a central server. The user joins the P2P network by simply installing the P2P software.
2
Q
Simple networks
A
consisting of two computers to networks
3
Q
Home office networks and small office networks
A
often set up by individuals that work from a home or a remote office and need to connect to a corporate network or other centralized resources.
4
Q
businesses and large organizations
A
networks can be used on an even broader scale to provide consolidation, storage, and access to information on network servers. Networks also allow for rapid communication such as email, instant messaging, and collaboration among employees. In addition to internal benefits, many organizations use their networks to provide products and services to customers through their connection to the Internet.
5
Q
Small Home Networks
A
Small home networks connect a few computers to each other and the internet
6
Q
Small office/ Home Office Networks
A
The small office/Home Office or SOHO network enables computers within a home office or a remote office to connect to a corporate network or access centralized, shared resources.
7
Q
Medium to Large Networks
A
Medium to large networks such as those used by corporations and schools, can have many locations with hundreds or thousands of interconnected computers.
8
Q
World Wide Networks
A
The internet is a network of networks that connects hundreds of millions of computers world-wide
9
Q
hosts
A
All computers connected to a network that participate directly in network communication are classified as hosts. Hosts are also called end devices.
10
Q
Servers
A
are computers with software that enable them to provide information, like email or web pages, to other end devices on the network. Each service requires separate server software.
11
Q
Clients
A
are computers with software installed that enable them to request and display the information obtained from the server.
12
Q
File Client and Server
A
The File Server stores corporate and user files in a central location. The client devices access these files with client software such as windows Explorer.
13
Q
Web Client and Server
A
The web server runs web server software and clients use their browser software, such as windows internet explorer, to access web pages on the server.
14
Q
Email Client and Server
A
The Email Server runs email server software and clients use their mail client software, such as Microsoft Outlook, to access email on the server.
15
Q
Peer-to-Peer
A
Client and server software usually runs on separate computers, but it is also possible for one computer to carry out 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.
16
Q
The advantages of peer-to-peer networking:
A
- Easy to set up
- Less complexity
- Lower cost since network devices and dedicated servers may not be required
- Can be used for simple tasks such as transferring files and sharing printers.
17
Q
The Disadvantages of peer-to-peer networking:
A
- No centralized administration
- Not as secure
- Not scalable
- All devices may act as both clients and servers which can slow their performance
18
Q
The network infrastructure contains three categories of network components:
A
- Devices
- Media
- Services
19
Q
Devices and media
A
are the physical elements, or hardware, of the network. Hardware is often the visible components of the network platform such as a laptop, PC, switch, router, wireless access point, or the cabling used to connect the devices.
20
Q
Services
A
include many of the common network applications people use every day, like email hosting services and web hosting services.
21
Q
End Devices
A
The network devices that people are most familiar with are called end devices. An end device is either the source or destination of a message transmitted over the network.
To distinguish one end device from another, each end device on a network is identified by an address. When an end device initiates communication, it uses the address of the destination end device to specify where the message should be sent.
22
Q
Intermediary Network Devices
A
Intermediary devices connect the individual end devices to the network and 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.
23
Q
Intermediary network devices perform some or all of these functions:
A
- Regenerate and retransmit data signals
- Maintain information about what pathways exist through the network and internetwork
- Notify others devices of errors and communication failures
- Direct data along alternate pathways when there is a link failure
- Classify and direct messages according to priorities
- Permit or deny the flow of data, based on security settings
24
Q
medium
A
Communication across a network is carried on a medium. The medium provides the channel over which the message travels from source to destination.
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types of media
* Metallic wires within cables - data is encoded into electrical impulses
* Glass or plastic fibers (fiber optic cable) - data is encoded as pulses of light
* Wireless transmission - data is encoded using wavelengths from the electromagnetic spectrum
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Network Interface Card
A NIC, or LAN adapter, provides the physical connection to the network at the PC or other end device. The media that are connecting the PC to the networking device, plug directly into the NIC
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Physical Port
A connector or outlet on a networking device where the media is connected to an end device or another networking device.
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Interface
Specialized ports on a networking device that connect to individual networks. Because routers are used to interconnect networks, the ports on a router are referred to as network interfaces.
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Topology diagrams
They provide a visual map of how the network is connected.
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Physical topology diagrams
Identify the physical location of intermediary devices and cable installation.
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Logical topology diagrams
Identify devices, ports, and addressing scheme
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Network infrastructures can vary greatly in terms of:
* Size of the area covered
* Number of users connected
* Number and types of services available
* Area of responsibility
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Local Area Network (LAN)
A network infrastructure that provides access to users and end devices in a small geographical area, which is typically an enterprise, home, or small business network owned and managed by an individual or IT department.
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Wide Area Network (WAN)
A network infrastructure that provides access to other networks over a wide geographical area, which is typically owned and managed by a telecommunications service provider.
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Metropolitan Area Network (MAN)
A network infrastructure that spans a physical area larger than a LAN but smaller than a WAN (e.g., a city). MANs are typically operated by a single entity such as a large organization.
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Wireless LAN (WLAN)
Similar to a LAN but wirelessly interconnects users and end points in a small geographical area.
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Storage Area Network (SAN)
A network infrastructure designed to support file servers and provide data storage, retrieval, and replication.
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Specific features of LANs include:
* LANs interconnect end devices in a limited area such as a home, school, office building, or campus.
* A LAN is usually administered by a single organization or individual. The administrative control that governs the security and access control policies are enforced on the network level.
* LANs provide high speed bandwidth to internal end devices and intermediary devices.
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Specific features of WANs include:
* WANs interconnect LANs over wide geographical areas such as between cities, states, provinces, countries, or continents.
* WANs are usually administered by multiple service providers.
* WANs typically provide slower speed links between LANs.
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The Internet
The Internet is a worldwide collection of interconnected networks (internetworks or internet for short). Some of the LAN examples are connected to each other through a WAN connection. WANs are then connected to each other.
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There are organizations that have been developed for the purpose of helping to maintain structure and standardization of Internet protocols and processes.
These organizations include the Internet Engineering Task Force (IETF), Internet Corporation for Assigned Names and Numbers (ICANN), and the Internet Architecture Board (IAB)
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Intranet
is a term often used to refer to a private connection of LANs and WANs that belongs to an organization, and is designed to be accessible only by the organization's members, employees, or others with authorization.
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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.
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Examples of extranets include:
* 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.
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Home users, teleworkers (remote workers), and small offices require a what to connect to the Internet.
typically require a connection to an Internet Service Provider (ISP) to access the Internet.
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Connection Options
. Connection options vary greatly between ISP and geographical location. However, popular choices include broadband cable, broadband digital subscriber line (DSL), wireless WANs, and mobile services.
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Business-class interconnections
are usually provided by service providers (SP). Popular business-class services include business DSL, leased lines, and Metro Ethernet.
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Cable
Typically offered by cable television service providers, the Internet data signal is carried on the same cable that delivers cable television. It provides a high bandwidth, always on, connection to the Internet.
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DSL
Digital Subscriber Lines provide a high bandwidth, 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.
50
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 will be limited by the capabilities of the phone and the cell tower to which it is connected.
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Satellite
The availability of satellite Internet access is a real benefit in those areas that would otherwise have no Internet connectivity at all. Satellite dishes require a clear line of sight to the satellite.
52
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 usually not sufficient for large data transfer, although it is useful for mobile access while traveling.
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fiber optic cables
Many homes and small offices are more commonly being connected directly with fiber optic cables. This enables an ISP to provide higher bandwidth speeds and support more services such as Internet, phone, and TV.
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Corporate connection options
Businesses may require higher bandwidth, dedicated bandwidth, and managed services. Connection options available differ depending on the type of service providers located nearby.
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Dedicated Leased Line
Leased lines are actually reserved circuits within the service provider’s network that connect geographically separated offices for private voice and/or data networking. The circuits are typically rented at a monthly or yearly rate. They can be expensive.
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Ethernet WAN
Ethernet WANs extend LAN access technology into the WAN.
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DSL
Business DSL is available in various formats. A popular choice is Symmetric Digital Subscriber Lines (SDSL) which is similar to the consumer version of DSL, but provides uploads and downloads at the same speeds.
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Satellite
- Similar to small office and home office users, satellite service can provide a connection when a wired solution is not available
59
Converging Network
Today, the separate data, telephone, and video networks are converging. Unlike dedicated networks, converged networks are capable of delivering data, voice, and video between many different types of devices over the same network infrastructure,
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Network Architecture
Networks must support a wide range of applications and services, as well as operate over many different types of cables and devices, which make up the physical infrastructure. The term network architecture, in this context, refers to the technologies that support the infrastructure and the programmed services and rules, or protocols, that move data across the network.
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four basic characteristics that the underlying architectures need to address in order to meet user expectations:
* Fault Tolerance
* Scalability
* Quality of Service (QoS)
* Security
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Fault Tolerance
This requires a network architecture that is built to be fault tolerant. A fault tolerant network is one that limits the impact of a failure, so that the fewest number of devices are affected.It is also built in a way that allows 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 can be instantly sent over a different link. Having multiple paths to a destination is known as redundancy.
63
packet-switched network
Packet switching splits traffic into packets that are routed over a shared network. A single message, such as an email or a video stream, is broken into multiple message blocks, called packets. Each packet has the necessary addressing information of the source and destination of the message. The routers within the network switch the packets based on the condition of the network at that moment. This means that all the packets in a single message could take very different paths to the destination.
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circuit-switched networks
A circuit-switched network is one that establishes a dedicated circuit between the source and destination before the users may communicate. If the call is unexpectedly terminated, the users must initiate a new connection.
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Scalability
A scalable network can expand quickly to support new users and applications without impacting the performance of the service being delivered to existing users.
In addition, networks are scalable because the designers follow accepted standards and protocols. This allows software and hardware vendors to focus on improving products and services without worrying about designing a new set of rules for operating within the network.
66
Quality of Service (QoS)
New applications available to users over internetworks, such as voice and live video transmissions, create higher expectations for the quality of the delivered services. 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 bandwidth is measured in the number of bits that can be transmitted in a single second, or bits per second (bps). When simultaneous communications are attempted across the network, the demand for network bandwidth can exceed its availability, creating network congestion.
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Queue
When the volume of traffic is greater than what can be transported across the network, devices queue, or hold, the packets in memory until resources become available to transmit them.
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Security
The network infrastructure, services, and the data contained on network-attached devices are crucial personal and business assets. There are two types of network security concerns that must be addressed: network infrastructure security and information security.
69
Securing a network infrastructure includes
the physical securing of devices that provide network connectivity, and preventing unauthorized access to the management software that resides on them
70
Information security
refers to protecting the information contained within the packets being transmitted over the network and the information stored on network attached devices.
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In order to achieve the goals of network security, there are three primary requirements
Confidentiality
Integrity
Availability
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Confidentiality
Data confidentiality means that only the intended and authorized recipients can access and read data.
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Integrity
Data integrity means having the assurance that the information has not been altered in transmission, from origin to destination.
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Availability
Data availability means having the assurance of timely and reliable access to data services for authorized users.
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New Network Trends
* Bring Your Own Device (BYOD)
* Online collaboration
* Video communications
* Cloud computing
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Bring Your Own Device
The concept of any device, to any content, in any manner, is a major global trend that requires significant changes to the way devices are used. This trend is known as Bring Your Own Device (BYOD).
BYOD is about end users having the freedom to use personal tools to access information and communicate across a business or campus network.
These personal tools include laptops, netbooks, tablets, smartphones, and e-readers. These can be devices purchased by the company or school, purchased by the individual, or both.
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Online Collaboration
For businesses, collaboration is a critical and strategic priority that organizations are using to remain competitive. Collaboration is also a priority in education. Students need to collaborate to assist each other in learning, to develop team skills used in the work force, and to work together on team-based projects.
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Video Communication
Video conferencing is a powerful tool for communicating with others at a distance, both locally and globally. Video is becoming a critical requirement for effective collaboration as organizations extend across geographic and cultural boundaries.
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Cloud Computing
Cloud computing allows us to store personal files, even backup our entire hard disk 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 IT's capabilities 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 anywhere in the world without compromising security or function.
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There are four primary types of Clouds,
: Public Clouds, Private Clouds, Hybrid Clouds, and Custom Clouds.
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data center
A data center is a facility used to house computer systems and associated components. A data center can occupy one room of a building, one or more floors, or an entire building. Data centers are typically very expensive to build and maintain. For this reason, only large organizations use privately built data centers to house their data and provide services to users. Smaller organizations that cannot afford to maintain their own private data center can reduce the overall cost of ownership by leasing server and storage services from a larger data center organization in the Cloud.
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Custom clouds
The most common vector for data loss includes instant messaging software and social media sites. For instance intercepted email or IM messages could be captured and reveal confidential information.
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Hybrid clouds
A hybrid cloud is made up of two or more clouds (example: part custom, part public), where each part remains a distinctive object, but both are connected using a single architecture. Individuals on a hybrid cloud would be able to have degrees of access to various services based on user access rights.
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Private Clouds
Cloud-based applications and services offered in a private cloud are intended for a specific organization or entity, such as the government. A private cloud can be set up using the organization’s private network, though this can be expensive to build and maintain. A private cloud can also be managed by an outside organization with strict access security.
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Public clouds
Cloud-based applications and services offered in a public cloud are made available to the general population. Services may be free or offered on a pay-per-use model, such as paying for online storage. The public cloud uses the internet to provide services.
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‘smart home technology’
Smart home technology is technology that is integrated into every-day appliances allowing them to interconnect with other devices, making them more ‘smart’ or automated.
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Powerline Networking
Powerline networking is an emerging trend for home networking that uses existing electrical wiring to connect devices,
The concept of “no new wires” means the ability to connect a device to the network wherever there is an electrical outlet. This saves the cost of installing data cables and without any additional cost to the electrical bill. Using the same wiring that delivers electricity, powerline networking sends information by sending data on certain frequencies.
Using a standard powerline adapter, devices can connect to the LAN wherever there is an electrical outlet. Powerline networking is especially useful when wireless access points cannot be used or cannot reach all the devices in the home. Powerline networking is not designed to be a substitute for dedicated cabling in data networks. However, it is an alternative when data network cables or wireless communications are not a viable option.
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Wireless Internet Service Provider (WISP)
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.
Although a separate transmission tower may be installed for the antenna, it is common that the antenna is attached to an existing elevated structure, such as a water tower or a radio tower. A small dish or antenna is installed on the subscriber’s roof in range of the WISP transmitter. The subscriber’s access unit is connected to the wired network inside the home. From the perspective of the home user, the setup is not much different than DSL or cable service. The main difference is that the connection from the home to the ISP is wireless instead of a physical cable.
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Wireless Broadband Service
Another wireless solution for the home and small businesses is wireless broadband, as shown in the figure. This uses the same cellular technology used to access the Internet with a smart phone or tablet. An antenna is installed outside the house providing either wireless or wired connectivity for devices in the home. In many areas, home wireless broadband is competing directly with DSL and cable services.
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Security Threats
Network security is an integral part of computer networking, regardless of whether the network is limited to a home environment with a single connection to the Internet or as large as a corporation with thousands of users. The network security that is implemented must take into account the environment, as well as the tools and requirements of the network. It must be able to secure data while still allowing for the quality of service that is expected of the network.
Securing a network involves protocols, technologies, devices, tools, and techniques to secure data and mitigate threats. Threat vectors may be external or internal. Many external network security threats today are spread over the Internet.
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Viruses, worms, and Trojan horses
malicious software and arbitrary code running on a user device
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Spyware and adware
software installed on a user device that secretly collects information about the user
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Zero-day attacks, also called zero-hour attacks
an attack that occurs on the first day that a vulnerability becomes known
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Hacker attacks
an attack by a knowledgeable person to user devices or network resources
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Denial of service attacks
attacks designed to slow or crash applications and processes on a network device
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Data interception and theft
an attack to capture private information from an organization’s network
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Identity theft
an attack to steal the login credentials of a user in order to access private data
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internal threats
There have been many studies that show that the most common data breaches happen because of internal users of the network. This can be attributed to lost or stolen devices, accidental misuse by employees, and in the business environment, even malicious employees. With the evolving BYOD strategies, corporate data is much more vulnerable. Therefore, when developing a security policy, it is important to address both external and internal security threats.
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Security Solutions
No single solution can protect the network from the variety of threats that exist. For this reason, security should be implemented in multiple layers, using more than one security solution. If one security component fails to identify and protect the network, others still stand.
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A home network security implementation
It is generally implemented on the connecting end devices, as well as at the point of connection to the Internet, and can even rely on contracted services from the ISP.
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network security implementation for a corporate network
usually consists of many components built into the network to monitor and filter traffic. Ideally, all components work together, which minimizes maintenance and improves security.
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Network security components for a home or small office network should include, at a minimum:
* Antivirus and antispyware – These are used to protect end devices from becoming infected with malicious software.
* Firewall filtering – This is used to block unauthorized access to the network. This may include a host-based firewall system that is implemented to prevent 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.
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In addition to the above, larger networks and corporate networks often have other security requirements:
* Dedicated firewall systems – These are used to provide more advanced firewall capabilities that can filter large amounts of traffic with more granularity.
* Access control lists (ACL) – These are used to further filter access and traffic forwarding.
* Intrusion prevention systems (IPS) – These are used to identify fast-spreading threats, such as zero-day or zero-hour attacks.
* Virtual private networks (VPN) – These are used to provide secure access to remote workers.
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Network security requirements
must take into account the network environment, as well as the various applications, and computing requirements. Both home environments and businesses must be able to secure their data while still allowing for the quality of service that is expected of each technology. Additionally, the security solution implemented must be adaptable to the growing and changing trends of the network.
