Week 3 - Network and cloud infrastructure Flashcards
What is the IT environment used to host?
Data
Services
Applications
Traditional IT Infrastructure
Infrastructure is…
Owned
Controlled
Operated
Managed
…by same organisation.
All hardware is owned by the organisation
Upfront commitment to fixed set of resources
Complete control over set of resources
Staff needed to manage resources:
- Hardware Maintenance
- Software Configuration
- Physical Security
- Software Security
If demand require less/more resources, it cannot be
easily added/removed
Organisation is responsible for resiliency and backup
– Resources required for data backup
– Resources required for server resilience
Applications must be designed with fixed set of resources in mind
Fast connectivity in cases where there is a direct ethernet connection
Data centre
Facility that centralizes
organisation/department IT
operations and hardware
Stores critical computing
and storage hardware
Enables delivery of shared
applications and data
Virtualisation commonly
used to optimize resource
utilisation
The ‘Cloud’
Cloud is not a physical thing
Abstract concept referring
to computer resources that:
- Is on a network at a
remote location - Provides services to other computers over the
network - Is managed by a 3rd Party
Cloud Environment
Cloud is a network of servers
Each server has different
function/s
Example:
Server for compute power
Server for data management
Server for a messaging
application
Cloud providers
Companies offering remote computing resources
are called cloud providers
Users of these remote computing resources pay per usage
Often calculated as a function of time and resource size
Cloud Characteristics
On Demand Self Service:
Consumer can provision computing capacity, such as server
time and network storage, automatically as needed without
requiring human interaction with each server provider.
Broad Network Access:
Accessed via multiple device types
Resource Pooling:
Providers computing resources are pooled to serve
multiple consumers using multi tenant model.
Different physical and virtual resources dynamically
assigned and reassigned according to consumer demand
Rapid Elasticity:
Capabilities can be dynamically provisioned and released
Measured Service:
Resource usage can be monitored, controlled and reported.
Provided transparency for consumer and provider
Benefits of Cloud vs Traditional IT
Cost:
No up front capital expense required to purchase hardware and
software
Less IT staff needed for managing infrastructure
Lower costs on electricity (powering servers and cooling)
Flexibility:
Easy to scale up or down depending on current business
demands
Secure Backup:
In cases of physical damage to local hardware, cloud stored
data can still be accessed
Reliability:
Data backup, disaster recovery and business continuity easier
Data backup, disaster recovery and business continuity easier and less expensive.
Data can easily be mirrored at multiple redundant sites
Mobility:
Data and applications are available to consumers wherever they are in the world
Disadvantages of Cloud vs Traditional IT
Downtime:
Cloud computing systems are internet based and access is
dependent on consumer internet connection
Internet service outage, or poor performance, will cause issues
Cost:
While cost is a key advantage of cloud, improper usage of the
system can result in costs increasing drastically.
Security:
While cloud providers are secure, consumers have less control
over the security vs traditional IT
Data breaches can occur via hacking
Data Transfer Costs:
Uploading data to the cloud is commonly inexpensive/free
however downloading data over basic monthly allowances can
incur charges per GB.
Customer Support:
Providers usually charge high fees to provide support.
Cloud service models
- Infrastructure as a Service
- Platform as a Service
- Software as a Service
What is a server?
Computer Resource:
1. On a network
2. Provides services/web-pages to Other Computers over Network
Web browser
Client Application
Retrieves and Presents information from World Wide Web
Web Page Stored in Hyper Text Mark-up Language (HTML)
Standardized way of representing web content
Browser reads HTML and displays information the way the web page developer designed the page to be
seen
Using TCP/IP, makes requests using Hyper Text Transport Protocol (HTTP)
Web server
A network computer with the primary role of serving Web pages to clients on request
Can also host a Web site along with images, style sheets, and other content - Clients (Web browsers) can access the Web pages
Uses Hyper Text Transfer Protocol (HTTP)
Receives HTTP requests from clients
Processes and replies to these requests
HTTP
Hyper Text Transfer Protocol
TCP/IP Application Layer Protocol
Request - Response Protocol
Client Submits HTTP request to server
Server returns a response message to the client
Completion Status
Requested Content
HTTP Session
Sequence of Request- Response transactions
Client initiates connection (3 Way Handshake)
Connection established using TCP on particular port
