Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

computer science ongoing flashcards > Set 10 > Flashcards

Set 10 Flashcards

1
Q

What is a first class object?

A

First class objects are objects which may:
- R - be returned in function calls
- A - be assigned as arguments
- V - be assigned to a variable
- E - appear in expressions

Functions are first-class objects in functional programming languages

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What does function application mean?

A

Applying a function to its arguments

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What does partial function application mean?

A

Parțial function application means only applying a function to some of its arguments. The result is a function.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is functional composition?

A
  • Combining two functions to get a new function
  • g*f means apply f first, then g
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Describe in words what map does

A

Applies a given function to each element of a list, returning a list of results

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Describe in words what filter does

A

Processes a list to produce a new list containing exactly those elements that match a given condition

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Describe in words what fold does

A

Reduces a list of values to a single value by repeatedly applying a combining function to the list values

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is the purpose of a domain name?

A
  • A domain name identifies an organisation or individual on the internet.
  • They use alphanumeric characters which make them easier for humans to remember than IP addresses
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is the purpose of a domain name server?

A

To translate a fully qualified domain name into its corresponding IP address

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is the domain name system?

A
  • The domain name system is a distributed database of mappings from FQDNs to their corresponding IP addresses
  • DNS servers are organised into a hierarchy
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What happens is a domain name server cannot resolve a lookup?

A

The query will be passed to another DNS server

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Who manages top level domains?

A
  • An (internet) registry
  • Each TLD may have restrictions as to who can use it
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is the main responsibility of an internet registry?

A

To maintain a definitive register of who owns a specific domain.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Give two examples of top level domains

A

.uk .org

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is meant by baud rate?

A

The maximum number of signal changes in a medium per second

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is meant by bit rate?

A

The number of bits transmitted over a medium per second

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Bit rate equation

A

bit rate of channel = (baud rate) x (number of bits per signal change)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is Serial Data Transmission?

A

Bits are sent one after the other over a single wire from source to destination

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is Parallel Data transmission?

A
  • Multiple bits are sent simultaneously over multiple wires from source to destination
  • Each bit is sent down a different wire
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

2 problems with Parallel Data transmission

A
  • Unreliable because of skew
  • Parallel wires also suffer from crosstalk
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is skew?

A

As each wire has slightly different properties, there is a possibility bits could travel different speeds over each of the wires and arrive at different times, meaning the signals might overlap

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What is cross-talk?

A

Interference between different lines, which causes data corruption

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

3 advantages of serial over parallel transmission

A
  1. Serial transmission doesn’t suffer from skew or cross-talk
  2. Serial is reliable over much longer distances
  3. Serial transmissions tends to be cheaper, as there is much less complexity and the physical size of cables is smaller
24
Q

What is bandwidth? What unit is it measured in?

A
  • A measure of the maximum capacity of a communication channel
  • It is directly proportional to bit rate
  • Measured in bits per second
25
Q

What is latency?

A

A time delay before some component in a computer system responds to an instruction

26
Q

What is synchronous transmission?

A
  • Data is transferred at regular intervals, synchronised by a clock signal
  • Receiver and transmitter clocks are synchronised
27
Q

What is asynchronous transmission?

A
  • Receiver and transmitter clocks only need to be synchronised for the duration of data transmission
  • Blocks of data are sent as soon as they are ready
28
Q

How are start and stop bits used in asynchronous transmission?

A
  • Start bit is sent to synchronise the clock in the receiver to the transmitter clock
  • Stop bit allows the receiver time to process the current block of data before another is sent
  • Stop bit is opposite to start bit to allows the next start bit to be recognised
29
Q

What is a proxy server?

A
  • A server that sits ​between the network hosts and the firewall
  • Packets are sent outside the network by the proxy server (on behalf of the network hosts)
  • Provides anonymity, caching, and logging of user activities
30
Q

What is a worm?

A

A piece of malicious software that can self-replicate between computers, either within a network (such as the Internet) or by a user downloading and running and malicious files.

Unlike viruses, worms are complete programs - they do not require a host program to cause damage.

31
Q

What is a virus?

A
  • A virus is a small program of self-replicating software that is attached to other program or files
  • Viruses require a host file in which to reside
32
Q

What is a trojan?

A
  • A type of malware that is disguised as a legitimate benign file that users can be tricked into opening
  • They can delete and modify data and allow more malware in once they are opened
33
Q

3 ways to prevent malware

A
  1. Improving code quality
  2. Monitoring
  3. Protection (e.g. up to date antivirus programs)
34
Q

What is a network topolgy?

A

The way a network and its connected devices (computers, printers, servers etc.) are connected

35
Q

3 disadvantages of bus networks

A
  1. If main cable fails no network data can be transmitted
  2. Performance degrades heavily with increased traffic
  3. Security is poor as all computers on the network can see all transmissions
36
Q

2 disadvantages of star networks

A
  1. If central node goes down the whole network can’t transmit / receive data
  2. Can be costly to set up and install as lots of cabling is needed
37
Q

What is the purpose of DHCP?

A

To automate the allocation of IP addresses (configuration) to hosts on a network

38
Q

Why is DHCP used?

A
  • Reduces the need for expert knowledge when configuring a host
  • Reduces the time required to configure hosts
39
Q

How is an IP address configured using DHCP?

A
  1. Host sends request to discover a DHCP server
  2. DHCP server offers configuration to host
  3. Host accepts configuration by echoing the accepted configuration back to the server
  4. DHCP server confirms that configuration has been allocated to host
40
Q

What does a firewall do?

A

Blocks or allows network traffic, based on predefined or dynamic rules and policies

41
Q

What is packet filtering?

A

When a firewall monitors outgoing and incoming packets and allowing them to pass or halt based on
- source and destination IP addresses
- protocols / ports

  • Each packet is analysed separately
42
Q

What is stateful inspection?

A
  • When the firewall monitors the incoming and outgoing traffic from all ongoing TCP connections by:
    – Analysing packet types
    – Inspecting the payload
    – Checking for suspicious activity (eg lots of outgoing data)
  • Connected packets are analysed together
43
Q

How long is an IPv4 address and what is it split into?

A
  • 32 bits (e.g. 192.168. 10.150)
  • Network ID and Host ID
44
Q

What is a subnet mask used for?

A

Identifying the Network ID part of an IP address (bitwise AND operation applied to subnet mask and IP address)

45
Q

How long is an IPv6 address and why was it introduced?

A
  • 128 bits (e.g. 2001:0db8:85a3:0000:0000:8a2e:0370:73)
  • Introduced to ensure there would be enough addresses for all devices to have a unique one - as IPv4 addresses are running out
46
Q

What is the difference between routable and non-routable IP addresses?

A
  • Routable IP Addresses must be public addresses. They are unique on a global scale, and are allocated by a regional issuing authority.
  • Non-routable IP addresses are assigned internally to devices on a private network. Many devices may have the same private address.
47
Q

What is NAT?

A
  • A process in which a router translates one or more non-routable IP addresses into one or more routable IP addresses and vice versa in order to provide Internet access to the local hosts
  • A single routable IP address can be used for an entire private network
48
Q

What is port forwarding?

A
  • An application of network address translation (NAT) that redirects a communication request for the public IP address using a specific port to a pre-selected private host
  • The port number is unchanged (forwarded)
49
Q

What is the purpose of port forwarding?

A
  • Allows computers outside the LAN to connect to a specific computer (and port) within the LAN
  • Needed if you want to have a (web) server inside the LAN
50
Q

How to determine if two computers are on the same subnet

A

Bitwise AND operation of subnet mask with both computer’s IP addresses. The result of the AND operations are the network IDs. These are then compared.

51
Q

How does routing work?

A
  • Routers are organised into a hierarchy
  • The path to take is selected by each router, determined by the Network ID of the destination IP address
  • Each router decrements the “time to live” of the packets
  • Source and destination MAC addresses changed at each hop
  • Network Address Translation will occur at routers at either end
52
Q

Explain how a router can be been configured so that a Web Server on a LAN can be accessed by computers outside the LAN

A
  • Port forwarding
  • Router must forward all traffic arriving on the HTTP(S) port to the IP address of the Web Server
53
Q

What is a client port?

A

A port automatically allocated to a client that is temporarily assigned and only exists for the duration of a connection.

54
Q

Which of packet filtering and stateful inspection are more advanced?

A

Stateful inspection

55
Q

3 things that are better about IPv6

A
  • There aren’t enough unique addresses in IPv4 - there are many more IPv6 addresses as they are much longer
  • IPv6 eliminates the need for NAT
  • Automatic host configuration is possible without DHCP
56
Q

Which host ID is reserved as a network identifier?

A

Host ID = all zeros

57
Q

State the name of the problem that RTS/CTS overcomes

A

The Hidden Node problem

computer science ongoing flashcards (11 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions