Chapter 6 - Communication & Cloud Flashcards
LAN
Local Area Network. Connects computers that reside in a single geographic location.
Network
A collection of computers that communicate with one another over transmission lines or wirelessly.
WAN
Wide Area Network. Connects computers at different geographic locations.
An internet
A network of networks. Internets connect LANs, WANs, and other internets.
The Internet
The most famous internet.
Intranet
A private internet that is used exclusively within an organization.
Protocol
A set of rules that programs on two communicating devices follow.
SOHO
Small Office or a Home Office.
Switch
A special-purpose computer that receives and transmits wired traffic on the LAN.
LAN device
A small computer that has a switch and a device for wireless communication. Has devices for connecting to WAN and via WAN to the internet. (Wireless router).
NIC
Network Interface Card. A device that connects the computer’s or printer’s circuitry to the network wires.
UTP cable
Unshielded Twisted Pair cable. Standard Ethernet cable. Contains sets of wires that are twisted together to improve signal quality.
Optical Fiber Cable
Used for high bandwidths of data. The signals are light rays reflected inside a glass core.
Access Point
The component of the LAN device that processes wireless traffic and communicates with the wired switch.
Switch vs Access Point
Wired devices communicate through the switch. Wireless devices communicate through the access point. When a wired device communicates to a wireless device, and vice versa, the switch and access point communicate.
IEEE 802.3
The protocol for wired LAN connections. Also called Ethernet. Ethernet transmits speeds of 10, 100, and 1,000 Mbps.
IEEE 802.11
The protocol used for wireless network communications. Several versions exist. The current standard, 802.11n allows speeds up to 600 Mbps.
Bluetooth
A common wireless protocol. It transmits data over short distances, usually replacing cables.
3 Functions of an Internet Service Provider (ISP)
1) Provides a legitimate Internet address.
2) Serves as gateway to the Internet. Passes communications to and from the internet.
3) Pays for the Internet. Pays access fees and other charges.
DSL
Digital Subscriber Line. Operates over phone lines. Downstream up to 40 Mbps (10 Mbps in most areas).
Cable
Uses television cable lines for communications. Up to 50 Mbps downstream, but since data is shared from a distribution center in each neighborhood, performance depends on the number of users.
WAN Wireless Connection
Cellular Data, i.e. 4G. Average performance of 500 Kbps with peaks of 1.7 Mbps.
TCP/IP Protocol Architecture
5 protocol types arranged in layers.
Layer 5: Application
Enables communication among programs. HTTP, HTTPS, SMTP, FTP.
Layer 4: Transport
Reliable internet transport. TCP.
Layer 3: Internet
Internet routing. IP.
Layer 2: Data Link
Flow among switches and access points. 802.3 and 802.11.
Layer 1: Physical
Between two devices. 802.3 and 802.11.
HTTP
Hypertext Transport Protocol. The protocol used between browsers and Web servers. There is also a secure version called HTTPS.
SMTP
Simple Mail Transfer Protocol. Used for email transmissions.
FTP
File Transfer Protocol. Used to move files over the Internet.
The Web
Internet-based network of browsers and servers that process HTTP or HTTPS. When using FTP, you are using the Internet, but not the Web.
TCP
Transmission Control Protocol. Breaks traffic up into pieces and sends each piece. Ensures that each piece arrives at its destination. If a piece is lost or damaged, TCP detects it and retransmits that piece. TCP provides reliable internet transport.
IP
Internet Protocol. Specifies the routing of the pieces of your message through the networks that comprise any internet.
IP Address
A number that identifies a particular device. Public IP Addresses identify a particular device on the public Internet and are controlled by ICANN (Internet Corporation for Assigned Names and Numbers). Private IP Addresses identify a particular device on a private network. Their assignment is controlled within the LAN, usually by the LAN device.
Benefits of private IP addresses
Public IP addresses are conserved because all computers on the LAN use the same public IP address. You don’t have to register with ICANN. When you move around the Internet doesn’t have to change it’s routing mechanisms to find your new location.
IPv4
The standard four-decimal dotted notation for IP addresses. i.e. 165.193.123.253
Domain Name
A world-wide unique name that is affiliated with a public IP address. Domain names are also administered by ICANN.
URL
Uniform Resource Locator. An address on the Internet. Consists of a protocol (such as http:// or ftp://) followed by a domain name or public IP address.
VPN
Virtual Private Network. Uses the Internet to create the appearance of private point-to-point communications. The point-to-point connection is called a tunnel. Tunnels are encrypted to ensure security.
Three-Tier Architecture of a Web Server
- User Tier
- Server Tier
- Database Tier
Web Page
A document that is coded in one of the standard page markup languages. The most popular being HTML.
Web Servers
Programs that run on a server-tier computer and that manage HTTP traffic by sending and receiving Web pages to and from clients.
Commerce Server
A program that runs on a server-tier computer. Receives a request from users via the Web server, takes some action, and returns a response to the users via the Web server. Typical functions are to obtain product information from a database, manage items in the shopping cart, and coordinate the checkout process.
Web Farm
Multiple Web Servers that distribute the work load in order to minimize customer delays.
The Cloud
The elastic leasing of pooled computer resources over the Internet.
Elastic
The amount of resources leased can be increased or decreased dynamically, programmatically, in a short span of time, and that organizations pay for just the resources that they use.
Pooled
Many different organizations use the same physical hardware; they share that hardware through virtualization.
Cloud Positives
- small capital requirements
- speedy development
- superior flexibility and adaptability to growing or fluctuating demand
- known cost structure
- industry-wide economies of scale, hence cheaper
- possible best of breed security/disaster preparedness
- no obsolescence
Cloud Negatives (conversely in-house positives)
- dependency on vendor
- loss of control over data location
- little visibility into true security and disaster preparedness capabilities
In-house Negatives
- significant capital required
- significant development effort
- annual maintenance costs
- ongoing support costs
- staff and train personnel
- increased management requirements
- difficult or impossible to accommodate fluctuating demand
- cost uncertainties
- obsolescence
Private Cloud
In-house hosting, delivered via Web service standards, that can be configured dynamically. Economies of scale cannot be shared with others.
SaaS
Software as a Service. Provides not only hardware infrastructure, but also an operating system and application programs on top of that hardware. Salesforce.com, iCloud, Office 365.
PaaS
Platform as a Service. Vendors provide hosted computer, an operating system, and possibly a DBMS. Customers provide their own applications on top of the hosted platform. Microsoft Azure, Oracle On Demand.
IaaS
Infrastructure as a Service. Cloud hosting of a bare server computer or disk drive. Customer supplies OS, applications, DBMS. Amazon EC2, Amazon S3, Rackspace.
