2019(m/j) Flashcards
(21 cards)
state why there is a need for IPV6 addressing
The number of IP addresses needed will exceed the number available using
IPv4.
Explain why this IPv6 address would be an invalid IPv4 address.
- Too many digits per group
- Too many groups of digits
- The address is more than 32 bits / 4 bytes
- Colons are used as separators
Describe the transmission of data using a PSTN.
- The PSTN consists of many different types of communication lines
- Data is transmitted in both directions at the same time // (full) duplex
data transmission - The communication passes through different switching centres
Identify one benefit and one drawback of installing a dedicated line between the two
buildings
Benefit
* (Probably) faster connection / communication / transmission of data
* (Usually) more consistent transmission speed
* Improved security
Drawback
* Expensive to set-up / maintain
* Disruption to the dedicated line would leave no alternative
Explain the role of routers and gateways in a network.
Router:
* Connects two (or more) networks
* Can connect a network to a WAN // acts as the single access point
for«
* Receives packets and forwards towards the destination
* «using the IP address of the destination
* Assigns private IP addresses
* Operates between similar networks // networks using the same protocol
* Can be used to segment a network
Gateway:
* Connect two (or more) networks
* Can connect a network to a WAN // acts as the single access point
for«
* Receives packets and send packets towards the destination
* «using the IP address of the destination
* Assigns private IP addresses
* Connects two dissimilar networks // networks that use different
protocols
Identify three other types of server.
-file server
-print server
-web server
-proxy server
application server
State two benefits of Biyu using an interpreter instead of a compiler while writing the
program.
- Easier de-bugging
- «because errors can be corrected in real time
- The effect of any change made to the code can be seen immediately
- Parts of the program can be tested, without all the program code being
available
Explain why software is often developed using library files.
- The code is already written so the programmer is not starting over again
which saves time - The code will have been used by many people so it should be already
thoroughly tested and relatively error-free / won’t need re-testing - The programmer can use e.g. mathematical / graphics functions etc.
that he may not know how to code - Use of named library functions can simplify the program and make it
easier to read - The library routine code should conform to industry standards and
therefore contribute towards a more robust program
A processor’s instruction set can be grouped according to their function. For example, one
group is the input and output of data.
Identify two other groups of instructions.
- Data movement
- Arithmetic operations
- (Unconditional and conditional) jump instructions
- Compare instructions
- Modes of addressing
Describe the internal operation of a microphone.
- The microphone has a diaphragm / ribbon (accept equivalent)
- The incoming sound waves cause vibrations (of the diaphragm)
- «causing a coil to move past a magnet (dynamic microphone) //
changing the capacitance (condenser microphone) // deforms the
crystal (crystal microphone) etc. - An electrical signal is produced
Describe the internal operation of a laser printer
- The revolving drum is initially given an electrical charge
- A laser beam (bounces off moving mirrors) scans back and forth across
the drum - …discharging certain points (i.e. ‘drawing’ the letters and images to be
printed as a pattern of electrical charges) - The drum is coated with oppositely charged toner (which only sticks to
charged areas) - The drum rolls over electro-statically charged paper // Electro-statically
charged paper is fed (towards the drum) - The ‘pattern’ on the drum is transferred to the paper
- The paper is passed through the fuser to seal the image
- The electrical charge is removed from the drum // the excess toner is
collected
Describe progressive encoding.
- Stores all the scan lines for an entire frame // displays / records all the
frame data at the same time // not split into fields - Complete frames are displayed in sequence
- The rate of picture display is the same as the frame rate.
Explain the differences between Dynamic RAM and Static RAM.
- DRAM has to be refreshed / charged and SRAM does not require a
refresh - DRAM uses a single transistor and capacitor and SRAM uses more
than one transistor - DRAM stores each bit as a charge and in SRAM each bit is stored
using a flip-flop/latch - DRAM requires higher power consumption under low levels of access,
(which is significant when used in battery-powered devices because it
requires more circuitry for refreshing) // SRAM uses less power (no
need to refresh) - DRAM less expensive to purchase (requires fewer transistors) // SRAM
is more expensive to buy (as it requires more transistors) - DRAM has slower access time/speed (because it needs to be
refreshed) // SRAM has faster access times - DRAM can have higher storage/bit/data density // SRAM has lower
storage/bit/data density - DRAM used in main memory and SRAM used in cache memory
Define the term copyright.
Formal or legal recognition of ownership of the program // Formal or legal
restriction / permissions on use of the program // The intellectual property
rights to the program
Explain why Shazia does not want to use an open source licence.
She does not wish to release the source code
* She does not want anyone to be able to edit / modify / share the source
code/program
* She wants to make money from the program
Name and describe two software licences, other than open source that Shazia could
use.
Commercial Software
* The program is purchased for a fee
* It restricts the number of users/possible time period for use // Limited
number of installations allowed // Software key needed to install
* Source code not provided // source code protected / cannot be edited
* Anyone can purchase/download if agree to the terms
Shareware
* The program is free for a trial period // The (free) program may have
limited functionality // Need to purchase / enter details after trial
* Users do not have access to the source code // source code may not be
edited
* Users may re-distribute the software.
Freeware
* There is no charge for the software
* The software could still be copyrighted
* She can set her own restrictions on what a user can do with the
program
State what is meant by the term data redundancy.
Repeated / duplicated data
Explain how a relational database can help to reduce data redundancy.
- Because each record/piece of data is stored once and is referenced by
a (primary) key - Because data is stored in individual tables
- «and the tables are linked by relationships
- By the proper use of Primary and Foreign keys
- By enforcing referential integrity
- By going through the normalisation process
Explain the difference between security and integrity.
- Security ensures that data is safe from unauthorised access // safe from
loss - Integrity ensures that data is accurate / consistent / up to date
Name and describe two security features provided by a DBMS.
For example:
* Access rights // User accounts
* Restrict actions (e.g. read / read-write) of specific users // unauthorised
users cannot access the database
* Views
* Restrict which parts of the database specific users can see
* Password // Biometrics // PIN code
* Prevents unauthorised access
* Automatic Backup
* Create regular copies of data in case of loss
* Encryption
* Data is incomprehensible to unauthorised users
A …………………………………………………………… allows a developer to extract data from a
database.
A …………………………………………………………… enables a developer to create user-friendly
forms and reports.
- Query Processor
- Developer Interface
