Module 10: Practice Quiz

Question 1

The Great Firewall of China injects fake DNS A records to block individual connections.

Answer 1

False

Injection of DNS A records serve to block access by domain name. Using TCP RSTs will allow blocking of individual connections.

Question 2

The Great Firewall of China is likely managed by a single entity.

Answer 2

True

This central management allows for coordinated censorship efforts.

Question 3

The Great Firewall of China may block content based on which of the following characteristics?
* Keywords within the URL
* Images on webpage
* Destination IP
* All of the above

Answer 3

All of the above

The GFW operates in an on-path fashion, passively examining passing traffic. It may use any combinations of characteristics for filtering.

Question 4

Packet dropping is a scheme used to censor content. Which of the following statements characterize packet dropping? Select all that apply.
* Low cost to implement.
* Scales easily.
* Might block content otherwise deemed appropriate.
* Able to block a part of a webpage.

Answer 4

• Low cost to implement.
• Might block content otherwise deemed appropriate.

Packet dropping is an effective method for censorship due to its simplicity.

Question 5

The GFW can block a portion of a website using DNS poisoning.

Answer 5

False

DNS poisoning typically affects domain name resolution rather than specific portions of a website.

Question 6

Suppose a client in Cambridge makes a request to a website based in China. When does the GFW reset the connection?

Answer 6

After the ACK sent by the client in Cambridge

This timing allows the GFW to effectively control the connection before it is fully established.

Question 7

Consider the variance of censorship methods used. Select the statement which correctly describes the situation.
- Censorship methods are consistent across ISPs making it easy to measure DNS manipulation.
- Censorship methods are inconsistent across ISPs making it easy to measure DNS manipulation.
- Censorship methods are consistent across ISPs making it difficult to measure DNS manipulation.
- Censorship methods are inconsistent across ISPs making it difficult to measure DNS manipulation.

Answer 7

Censorship methods are inconsistent across ISPs making it difficult to measure DNS manipulation.

This inconsistency complicates efforts to assess the extent and nature of censorship.

Question 8

Current research methods for understanding DNS methods are scalable due to the number of volunteers participating.

T/F

Answer 8

False

Scalability is often limited by the resources and coordination required for effective data collection.

Question 9

The use of Open DNS resolvers resolves some of the ethical concerns associated with Internet censorship studies.

T/F

Answer 9

True

Open DNS resolvers can provide a more neutral ground for data collection in censorship studies.

Question 10

Iris uses —— to obtain a dataset for machine learning.

Answer 10

Open DNS Resolvers

This method leverages publicly available DNS services to gather data.

Question 11

SupposeIris is being used to detect DNS manipulation.Irisqueries a globalresolver for an IP addresses(consistency metric)and receivesa DNS Arecordwith a different IPaddress than the ones stored. Which of the follow statements are true?
- The response is inconsistent, and therefore will be classified as manipulated.
- The response is inconsistent, but might not be classified as manipulated.
- The response is consistent, and therefore will be classified as correct.
- The response is consistent, but might still be classified as manipulated.

Answer 11

The response is inconsistent, but might not be classified as manipulated.

The response is inconsistent, but will be classified as correct if the IP address satisfies an independent verifiability metric.

Question 12

Augur is used to identify DNS-based manipulations.

T/F

Answer 12

False

Augur is a method that utilizes TCP/IP side channels to measure reachability without controlling a measurement vantage point.

Question 13

Suppose we are using Augur to detectfiltering between two host, and that we havea scenario whereno blocking occurs. The measurementmachinesends a SYN-ACK to the reflector. What should happen?
- The return IP ID from the reflector to the measurement machine should increase by 2.
- The return IP ID from the reflector to the measurement machine should increase by 1.
- The return IP ID from the reflector to the measurement machine should remain the same.

Answer 13

The return IP ID from the reflector to the measurement machine should increase by 2.

This indicates that the connection is functioning normally without filtering.