Tutorial 3: 17th October 2019 Flashcards Preview

CS4105 Advanced Communication Networks and Systems > Tutorial 3: 17th October 2019 > Flashcards

Flashcards in Tutorial 3: 17th October 2019 Deck (26)
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1
Q

What factors should be considered during system design?

A

performance, cost, functionalitity, and scalability

2
Q

How does recovery compare between Reno and Cubic?

A

Reno recovers more slowly, especially at larger delays.

3
Q

Why was the cubic variant of TCP made?

A

Because of the slow recovery times of Reno TCP, especially at high delays, and in particular in the transmission of Physics test data.

4
Q

What has been the priority in the development of HTTP?

A

Performance

5
Q

What may you have to trade-off when designing protocols?

A

Some two properties, such as performance and scalability

6
Q

How do companies influence the development of new protocols?

A

Change or twist them to their interests (e.g. making their app faster) rather than for public interest as a whole

7
Q

What is IPSec?

A

IPSec = IP security = a suite of protocols that provide data authentication, integrity, and confidentiality.

8
Q

What is the difference between security and privacy on the Internet?

A

Privacy is the control one has over their data: who can see them and what they can do with them. Security is how information is protected: privacy is established.

9
Q

When could security be implemented but privacy not?

A

Encrypted packets are secure but not private since the sender and receiver are in plaintext headers. So can see URL you are at but not the POST/GET request data.

10
Q

What is TLS?

A

A cryptographic protocol implementing secure, encrypted communications over a network. It is at the transport and session layer and is on top of TCP, again providing an application interface for secure and encrypted communications.

11
Q

What is SSL?

A

A protocol that enables encrypted communications over a network (the Internet). SSL is at the transport layer, sitting on top of TCP, and provides an application interface for secure and encrypted communications.

12
Q

Where is TLS in the layered Internet protcol model?

A

A mixture of transport and session layers

13
Q

What does TLS do with HTTP?

A

Provides an interface to secure and encrypted comms.

14
Q

Which versions of HTTP can use TLS?

A

1.1 onwards.

15
Q

How does privacy and security change with HTTP3?

A

Forces the use of TLS and privacy and security features by default, giving a warning if not used.

16
Q

How does the comparison of nginx and Apache present an example of a tradeoff?

A

both better for different workloads: single v multi threading

17
Q

What important aspect of protocol/systems deployment do many university students and graduates fail to consider? Why?

A

deployment and scalability as never been issues with designs before as we control practicals

18
Q

What difficulties does the Interent add to protocol and service deployment?

A

Need to be interoperable with existing systems and protocols as well as number of devices to update

19
Q

What type of apps are particularly affected by firewall issues and NATs? Why?

A

real-time interactive apps. because they try to use new port numbers which interferes with NAT’s mapping mechanism (port number not global ID). So a presence/discovery mechanism is required on top of NAT due to a lack of global addresses.

20
Q

What are presence systems?

A

Methods by which users of a service inform others that they are present and available and willing to communicate.

21
Q

What are presence systems aka?

A

Discovery systems.

22
Q

When are presence systems required?

A

When there are no global IDs on a network so hosts can’t query other hosts themselves.

23
Q

Why may people want to use NAT with IPv6?

A

For privacy and to abstract a subnetwork connection.

24
Q

What is NPTv6?

A

NAT with IPv6.

25
Q

What unforeseen responsibility do staff in companies in the technology industry now have in regards to its development?

A

Ensuring it is in the best interest of the public and doesn’t take advantage of them or their influence.

26
Q

Can ILNP give NAT-like functionality? How?

A

Yes, in the rewriting mechanism. It gives NAT-like functionality whilst maintaining unique end-to-end identifiers.