Chapter 6 Summary

Q1:  Why Is the Cloud the Future for Most Organizations?

The cloud is the elastic leasing of pooled computer resources over the Internet.  The term cloud is used because most early diagrams of three-tier and other Internet-based systems used a cloud symbol to represent the Internet and organizations came to view their infrastructure as being "somewhat in the cloud."  The term elastic means that the computing resources leased can be increased or decreased dynamically, programmatically, in a short span of time and that organization pay for just the resources that they use.  Cloud sources are pooled because many different organizations use the same physical hardware; they share that hardware through virtualization.  Cloud vendors dynamically allocate virtual machines to physical hardware as customer needs increase or decrease.

Q2:  What Network Technology Supports the Cloud?

A computer network is a collection of computers that communicate with one another over transmission lines or wirelessly.  A local area network (LAN) connects computers that reside in a single geographic location on the premises of the company that operates the LAN.  A wide are network (WAN) connects computers at different geographic locations.  The computers in two separated company sites must be connected using a WAN.  The single versus multiple site distinction is important.  With a LAN, an organization can place communications lines wherever it wants because all lines reside on its premises.  An internet is a network of networks.  Internets connect LANs, WANs, and other internets.  The most famous internet is "the internet", the collection of networks that you use when you send email.

Q3:  How Does the Cloud Work?

An Internet address is called an IP address, which is a number that identifies a particular device.  Public IP addresses identify a particular device on the public Internet.  Because public IP addresses must be unique, worldwide, their assignment is controlled by a public agency known as ICANN (Internet Corporation for Assigned Names and Numbers).  Private IP addresses identify a particular device on a private network, usually on a LAN.  IP addresses have two formats.  The most common form, called IPv4 has a four decimal dotted notation.  the second called IPv6 has a longer format and will not concern us here.

Q4:  How Do Organizations Use the Cloud?

An organization that provides software as a service (SaaS) provides not only hardware infrastructure, but also an operating system and application programs as well.  The second category of cloud hosting is platform as a service (PaaS) whereby vendors provide hosted computers, an operating system, and possibly a DBMS.  The most basic cloud offering is infrastructure as a service (IaaS) which is the cloud hosting of a bare server computer or data storage.  A content delivery network (CDN) is a system of hardware and software that stores user data in many different geographical locations and makes those data available on demand.

Q5:  How Can AllRoad Parts Use the Cloud?

AllRoad Parts is a small company with a very small IT department.  Software as a service requires little investment in the hardware and software system components.  AllRoads leases hardware and operating systems in the cloud from the cloud vendor.

Q6:  How Can Organizations Use Cloud Service Security?

A virtual private network (VPN) uses the Internet to create the appearance of private, secure connections.  A private cloud is a cloud that is owned and operated by an organization for its own benefit.  A virtual  private cloud (VPC) is a subset of a public cloud that has highly restricted, secure access.  An organization can build its own VPC on top of public cloud infrastructure like AWS or that provided by other cloud vendors.