Wednesday, 6 May 2015

Home, work?!

How many Kilobytes in a Megabyte?
How many Megabytes in a Gigabyte?
1024 for both.






How Many Megs in 4 Terabytes?
1024 * 1024 * 4 = 4194304






How many Bits in a Petabyte?
8 bits in a byte
1024 bytes in kB
1024 kB in MB
1024 mB in GB
1024 GB in TB
1024 TB in PB
 
8 * 1024^5 = 9007199254740992
How many Bits in a Yotta? (jokes).
A Yottabyte is 1000^8 lol.

Tell me what Base 10, Base 2 and Base 16 are.
BASICALLY
B10 = Denary
B2 = Binary
B16 = Hex


Simple innit.














Tell me where Hexadecimal is used and why?


Colours in CSS due to its simplicity and large range.












Extension: Write a very simple Python program that works out bits/bytes OR that
converts Binary to Denary OR that converts Hex.


No :D

Tuesday, 5 May 2015

DNS

Notes:
DNS translates a URL into an IP address.
Browser and OS will determine if it knows the IP address from memory or cache.
If not, OS queries resolving name server for IP address
RNS communicates with root name servers for IP address
Which will link to the Top Level Domain name servers
RNS stores info from Root Name Servers in cache
Resolving queries TLD server, links to Autoritiative Name Server
ANS' controlled by registrar
Resolving Queries ANS, which provides IP.
Resolving replies to OS
which replies to Browser
Browser then loads web page




The purpose of DNS is to translate a web address into an IP address. When the user inputs the address into the browser, first the OS and browser check the Resolving Name Server to see if the IP is stored in memory. If not, the Root Name Server, Top Level Domain name server, and Authoritative Name Server will be queried, until the ANS responds with an IP. The Resolving Name Server updates it's cache with this information and then returns it to the OS. The browser will then access the page stored at that IP.

Advantages:


  • No need to memories numbers/makes the web more user friendly
  • Easier for search engines
Disadvantages:
  • Breakdown of DNS would destroy the WWW
  • Defeats the purpose of the internet being a decentralised system

Tuesday, 20 January 2015

Thing that was meant to be on PowToon but wasn't.

PowToon broke and deleted my work so this is the best I’ve got:

  • Syntax – The structure and rules of a programming language.
  • Overflow – When an integer is larger or smaller than what the computer can handle or display.
  • Strings – The data type used for text.
  • Erroneous – A piece of code which is broken, often due to a syntax error.
  • Variables – A label used to store a value or piece of data.
  • Logic/Logical – The logic used by a program, such as if statements and while loops to determine if something is True or not.
  • Run-time – What happens at the time the program compiles or runs.
  • Zero – A number with no real value, which also equates to False in programming. Also used as the starting index for lists and other things in programming.
  • Invalid – A data type being used incorrectly (for example, trying to add a string to an integer)
  • Validation – Ensures the data being used is fitting for its purpose (for example, if you made a program collecting people’s ages, you wouldn’t want to accept a string or Boolean value for an age)
  • Infinite Loops – When a condition is always True, the loop will repeat forever until the program is forcefully closed.
  • Extreme – A data value on the very edge of what can be deemed an acceptable value.