Tutorial 3: 17th October 2019 Flashcards
Design considerations of protocols and systems
What factors should be considered during system design?
performance, cost, functionalitity, and scalability
How does recovery compare between Reno and Cubic?
Reno recovers more slowly, especially at larger delays.
Why was the cubic variant of TCP made?
Because of the slow recovery times of Reno TCP, especially at high delays, and in particular in the transmission of Physics test data.
What has been the priority in the development of HTTP?
Performance
What may you have to trade-off when designing protocols?
Some two properties, such as performance and scalability
How do companies influence the development of new protocols?
Change or twist them to their interests (e.g. making their app faster) rather than for public interest as a whole
What is IPSec?
IPSec = IP security = a suite of protocols that provide data authentication, integrity, and confidentiality.
What is the difference between security and privacy on the Internet?
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.
When could security be implemented but privacy not?
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.
What is TLS?
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.
What is SSL?
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.
Where is TLS in the layered Internet protcol model?
A mixture of transport and session layers
What does TLS do with HTTP?
Provides an interface to secure and encrypted comms.
Which versions of HTTP can use TLS?
1.1 onwards.
How does privacy and security change with HTTP3?
Forces the use of TLS and privacy and security features by default, giving a warning if not used.
How does the comparison of nginx and Apache present an example of a tradeoff?
both better for different workloads: single v multi threading
What important aspect of protocol/systems deployment do many university students and graduates fail to consider? Why?
deployment and scalability as never been issues with designs before as we control practicals
What difficulties does the Interent add to protocol and service deployment?
Need to be interoperable with existing systems and protocols as well as number of devices to update
What type of apps are particularly affected by firewall issues and NATs? Why?
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.
What are presence systems?
Methods by which users of a service inform others that they are present and available and willing to communicate.
What are presence systems aka?
Discovery systems.
When are presence systems required?
When there are no global IDs on a network so hosts can’t query other hosts themselves.
Why may people want to use NAT with IPv6?
For privacy and to abstract a subnetwork connection.
What is NPTv6?
NAT with IPv6.
What unforeseen responsibility do staff in companies in the technology industry now have in regards to its development?
Ensuring it is in the best interest of the public and doesn’t take advantage of them or their influence.
Can ILNP give NAT-like functionality? How?
Yes, in the rewriting mechanism. It gives NAT-like functionality whilst maintaining unique end-to-end identifiers.
