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Higher Computing Help - URGENT! - HSN forum

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Higher Computing Help - URGENT!


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#1 Peter

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Posted 25 May 2005 - 01:43 PM

Can anybody help me with higher computing - need help with any thing do to with computer (mostly networking and things to do with performance checks etc, anything will do)
P.E.T.E.R

#2 Dave

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Posted 25 May 2005 - 01:47 PM

u need to be more exact

its not easy to teach you the whole course on a discussion board

If i am not here i am somewhere else



#3 Phoenix

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Posted 25 May 2005 - 03:34 PM

Summaries for networking: -

1. Common Network Protocols

•Telnet is a protocol used to connect to a remote computer
•FTP is a protocol used to transfer files to and from a remote computer
•HTTP is a protocol used to retrieve web pages and other files from a web serve
•SMTP is a protocol used to transfer email to a mail server
•POP3 is a protocol used to retrieve email from a mailbox on a mail server
•An email address consists of a username and a domain name separated by the @ symbol
•Telnet. FTP, HTTP, SMTP and POP3 all use plain text ASCII commands, although nowadays GUI front ends exist to make them easier to use
•TCP is a lower level protocol responsible for splitting a file to be transmitted into packets, each with a sequence number .
•IP is a lower layer protocol responsible for routing packets around between networks
•A combination of a port and a TCP/IP connection is called a socket and allows several virtual connections to run on one machine at the same time.

2. The OSI Networking Model

•The OSI model divides networks into seven layers
•Layers are hierarchical, transparent, and independent
•The Application layer provides interfaces for network applications
•The Presentation layer handles data format information
•The Session layer manages log-on and password authentication
•The Transport layer breaks up file into segment for transport over a network and guarantees that these segments are not lost
•The Network layer routes packets
•The Data Link layer guarantees error free transmission
•The Physical layer transmits bits over physical medium

3. IP addresses and the Domain Name Service•An IP address consists of four 8 bit numbers called octets
•An IP address can be divided into two sections – a network identifier and a host identifier.
•IP addresses can be classed as A B or C depending on the number of octets used as the host identifier
•Private IP addresses and a Proxy Server can be used on Local Area Networks to provide Network Address Translation (NAT)
•Static IP addressing is where every machine on a network has a fixed IP address
•Dynamic IP addressing is where an IP address is allocated from a pool of addresses
•The Domain Name Service translates user friendly domain names into IP addresses using Name Resolution

4. The World Wide Web (WWW)•Web pages are written using Hypertext Markup Language (HTML) which is interpreted by a browser to present the page on the screen for the user.
•HTML uses tags which define elements
•The structure of an HTML page is indicated by the <html> <head> and <body> tags
•Examples of text tags are <p> <b> and <h1>
•Elements have attributes which are additional information relating to the appearance or layout of that element
•XHTML is a stricter version of HTML which requires that all documents have a type declaration, all tags are properly closed, are in lower case and are properly nested
•Microbrowsers are designed for mobile devices with small screens and low bandwidth
•Applications written for microbrowsers use the Wireless Markup Language (WML)
•Indexed search engines use programs called spiders to hunt around the web for pages which are linked to pages already in their database
•Directory based search engines rely on human reviewers to create their database of links
•Meta search engines return results from a number of different search engines

5. Implications of the WWW• E-commerce is the buying or selling of goods or services over the Internet
•The advantages to the customer are convenience and increased choice
•The advantages to the retailer are economy of scale, increased markets and automation
•Disadvantages for both parities are the possibility of fraud, and the increased need for up-to date technology
•The internet can result in social problems such as the increasing gulf between the Information Rich and the Information Poor and increased social isolation
•Tele-working has the potential to improve peoples lives by reducing the need to travel and allowing them to work in their own home in their own time.
•Video conferencing also has the potential to reduce the need for travel, but currently needs special equipment and a high bandwidth connection
•Ethical implications of the WWW include the problem of personal privacy, the ability of others to track your use of the internet and the increased use of encryption to disguise illegal activities
•The use of chatrooms by young people and their exploitation by paedophiles is also an ethical concern.
•Computers and the Internet are regulated by a number of acts of parliament in the UK. These include the Copyright Act, the Data Protection Act, the Misuse Of Computers Act and the Regulation of Investigatory Powers Act

6. Network Security•Network security is always a compromise between security and convenience
•The purpose of network security is to protect data on the network, the network itself, and users of the network
•Threats to network security can be from both inside and outside an organisation
•Security inside a network is primarily enforced by user ID and password
•Security from outside is primarily enforced by ensuring that there is only one point of contact with the outside world
•The hardware and software resources which a user has access to are determined by the restriction policy linked to their ID
•Encrypting data files on a network can add a further level of security
•Hardware solutions to security concerns include physically locking up workstations, servers and backup tapes. User IDs can also be linked to biometric security systems
•Using a switched network, and making sure that wireless networks are secure reduces the chances of Ethernet packets being intercepted by someone who has managed to connect a rogue machine into the network.
•Wireless networks need to be configured to make them secure.
•Network servers and stations need to be protected from virus attack using anti-virus software. The anti-virus software should be kept up to date with virus signatures
•A firewall is software which blocks attack from outside, and restricts the transfer of packets from inside a network by examining the source and destination IP address and port number of every packet which passes through it

7. Denial of Service Attacks and Disaster Recovery•Denial of Service attacks are attempts to reduce the resources available to legitimate users of a server.
•DoS attacks can be physical attacks, or exploitation of careless network management.
•An example of the exploitation of software flaws is where the hacker crashes the server and then gains access via a debug mode.
•Resource starvation is where the server is flooded with ping messages or attacked with a virus or a worm
•DNS attacks are where DNS servers are used to launch a resource starvation attack.
•The effects of a DoS attack are loss of business, loss of trust, inconvenience and expense
•The reasons for a DoS attack may be political, economic or malicious.
•Disaster can be avoided by keeping regular and reliable backups and making sure that a robust backup strategy is in place.
•Backup tapes should normally be taken off site and kept in a secure location
•Hardware solutions include duplicate equipment, uninterruptible power supplies, and disk mirroring or RAID servers.

8. Data Transmission
•Bandwidth is normally described in terms of Kbps (Kilobits per second) or Mbps (Megabits per second)
•Asynchronous data transmission transmits one byte at a time along with start and stop bits
•Synchronous data transmission is more efficient because blocks of data are larger and less control information needs to be included
•Circuit switching maintains a fixed connection between two points while data is being transferred
•Packet switching is “Connectionless” because data is routed in packets which may take different routes
•The Ethernet standard uses Carrier Sense Multiple Access / Collision Detection (CSMA/CD) to ensure that packets of data do not interfere with each other on a network segment
•A switched Ethernet network has less collisions and is more secure because the switch effectively divides the network up into a number of separate segments
•Every Network Interface Card (NIC) has a unique MAC address to identify it. This is separate from the IP address which is controlled by software.
•Parity, Checksums and Cyclic Redundancy Checks are all methods of error detection in data transmission – all involve additional data being transmitted
•A Dialup Internet connection uses a modem and can achieve a maximum of 56Kbps
•An ISDN line and terminal adapter provides two 64Kbps digital channels and one 16Kbps control line
•An ADSL line is programmed to operate between two specific locations and can provide 2Mbps download and 128Kbps upload bandwidth. ADSL bandwidth may be shared between a number of users.
•A Cable modem provides similar bandwidth to an ADSL line but uses Television distribution cable to provide the connection
•A leased line provides a guaranteed 1.54 Mbps digital connection between two specific locations but is by far the most expensive option

9. Wireless Data Applications
•Wireless networking is still a relatively new technology and there are a wide variety of standards available to implement Personal, Local or Wide area networks.
•Personal wireless area networks tend to be low bandwidth and short range and are used for linking portable communications equipment
•Wireless local area networks tend to be high bandwidth and medium range and are used for connecting portable machines to conventional cabled networks or replacing cabled networks
•Wireless wide area networks tend to be mid bandwidth and high range and are used to provide broadband services to users who do not have access to wired systems.


Hope that helps smile.gif


#4 Shaun

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Posted 25 May 2005 - 03:37 PM

Good note!

#5 Chnz

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Posted 25 May 2005 - 07:55 PM

Wow... well it looks like I'll be studyin that list tomorrow!

#6 adilxs

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Posted 27 May 2005 - 06:45 PM

thanks, looks good

#7 rossco

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Posted 27 May 2005 - 09:53 PM

Ye that will help. Thanks! biggrin.gif





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