DNS poisoning in Computer Networks - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the sentence to define DNS poisoning.

Computer Networks

DNS poisoning is a type of attack where false [1] are inserted into a DNS resolver's cache.

Drag options to blanks, or click blank then click option'

Apasswords

Bdomain names

CIP addresses

Demails

Attempts:

3 left

💡 Hint

Common Mistakes

Confusing domain names with IP addresses.

DNS poisoning involves inserting false IP addresses into the DNS cache to redirect users to malicious sites.

2fill in blank

medium

Complete the sentence to explain the goal of DNS poisoning.

Computer Networks

The main goal of DNS poisoning is to redirect users to a [1] website instead of the legitimate one.

Drag options to blanks, or click blank then click option'

Amalicious

Bfast

Cofficial

Dsecure

Attempts:

3 left

💡 Hint

Common Mistakes

Choosing 'secure' or 'official' which are opposite of the attack's purpose.

Attackers redirect users to malicious websites to steal information or spread malware.

3fill in blank

hard

Fix the error in the sentence describing a DNS poisoning effect.

Computer Networks

DNS poisoning causes users to visit [1] IP addresses that attackers control.

Drag options to blanks, or click blank then click option'

Arandom

Bfake

Ctrusted

Dcorrect

Attempts:

3 left

💡 Hint

Common Mistakes

Choosing 'correct' or 'trusted' which contradict the attack nature.

The IP addresses are fake, set by attackers to mislead users.

4fill in blank

hard

Fill both blanks to describe how DNS poisoning works.

Computer Networks

Attackers inject [1] into the DNS cache, causing the resolver to return a [2] IP address.

Drag options to blanks, or click blank then click option'

Afalse records

Bcorrect

Cfake

Dencrypted data

Attempts:

3 left

💡 Hint

Common Mistakes

Choosing 'correct' or 'encrypted data' which do not fit the attack description.

Attackers insert false records so the DNS resolver returns fake IP addresses.

5fill in blank

hard

Fill all three blanks to complete the explanation of DNS poisoning consequences.

Computer Networks

Users are redirected to [1] sites where attackers can [2] sensitive data or [3] malware.

Drag options to blanks, or click blank then click option'

Amalicious

Bsteal

Cinstall

Dtrusted

Attempts:

3 left

💡 Hint

Common Mistakes

Choosing 'trusted' which is opposite of the attack's effect.

Malicious sites allow attackers to steal data or install malware on users' devices.

Practice

1. What is the main goal of DNS poisoning in computer networks?

easy

A. To block access to certain websites

B. To redirect users to fake websites by giving wrong IP addresses

C. To encrypt DNS queries for security

D. To speed up the DNS lookup process

Solution

1. Step 1: Understand DNS function

   DNS translates website names into IP addresses so computers can find websites.

2. Step 2: Identify DNS poisoning effect

   DNS poisoning gives wrong IP addresses, sending users to fake sites instead of real ones.

3. Final Answer:

   To redirect users to fake websites by giving wrong IP addresses -> Option B

4. Quick Check:

   DNS poisoning = Redirect to fake sites [OK]

Hint: DNS poisoning tricks DNS to give wrong addresses [OK]

Common Mistakes:

• Thinking DNS poisoning speeds up browsing
• Confusing DNS poisoning with encryption
• Believing it blocks websites instead of redirecting

2. Which of the following is a correct way to describe DNS poisoning?

easy

A. It modifies DNS cache with false information

B. It encrypts DNS queries to protect privacy

C. It speeds up DNS resolution by caching

D. It blocks DNS requests from unknown sources

Solution

1. Step 1: Recall DNS poisoning mechanism

   DNS poisoning involves changing DNS cache entries to wrong IP addresses.

2. Step 2: Match description to options

   Only It modifies DNS cache with false information correctly states DNS poisoning modifies DNS cache with false info.

3. Final Answer:

   It modifies DNS cache with false information -> Option A

4. Quick Check:

   DNS poisoning = false DNS cache entries [OK]

Hint: DNS poisoning changes DNS cache to wrong info [OK]

Common Mistakes:

• Confusing poisoning with encryption
• Thinking it speeds up DNS
• Assuming it blocks requests

3. Consider this scenario: A user tries to visit example.com. Due to DNS poisoning, the DNS cache returns the IP 192.0.2.123 instead of the real IP 93.184.216.34. What is the likely result?

medium

A. The user is redirected to a fake website at IP 192.0.2.123

B. The DNS query fails and the website doesn't load

C. The user reaches the real example.com website safely

D. The user's browser automatically blocks the connection

Solution

1. Step 1: Understand DNS poisoning effect on IP

   The DNS cache gives a wrong IP (192.0.2.123) instead of the real one (93.184.216.34).

2. Step 2: Predict user experience

   The user is sent to the wrong IP, likely a fake website pretending to be example.com.

3. Final Answer:

   The user is redirected to a fake website at IP 192.0.2.123 -> Option A

4. Quick Check:

   Wrong IP from DNS = fake site visit [OK]

Hint: Wrong IP from DNS means fake site shown [OK]

Common Mistakes:

• Assuming user reaches real site
• Thinking DNS query fails
• Believing browser blocks automatically

4. A network admin notices users are being redirected to suspicious sites. They suspect DNS poisoning. Which action will help fix this issue?

medium

A. Turn off the internet connection temporarily

B. Disable the firewall to allow all traffic

C. Change all user passwords immediately

D. Clear the DNS cache on affected devices and servers

Solution

1. Step 1: Identify how DNS poisoning affects devices

   DNS poisoning corrupts DNS cache with wrong IP addresses causing redirection.

2. Step 2: Choose corrective action

   Clearing DNS cache removes false entries, restoring correct address resolution.

3. Final Answer:

   Clear the DNS cache on affected devices and servers -> Option D

4. Quick Check:

   Fix DNS poisoning by clearing DNS cache [OK]

Hint: Clear DNS cache to remove poisoned entries [OK]

Common Mistakes:

• Disabling firewall worsens security
• Changing passwords doesn't fix DNS
• Turning off internet is impractical

5. A company wants to protect its users from DNS poisoning attacks. Which combined approach is best to reduce risk?

hard

A. Manually edit hosts files on all user devices

B. Only use public Wi-Fi networks and disable firewalls

C. Use DNSSEC to verify DNS data and configure trusted DNS servers

D. Rely solely on antivirus software for protection

Solution

1. Step 1: Understand DNSSEC and trusted DNS servers

   DNSSEC adds digital signatures to DNS data to verify authenticity. Trusted DNS servers reduce risk of poisoning.

2. Step 2: Evaluate options for protection

   Use DNSSEC to verify DNS data and configure trusted DNS servers combines verification and trusted sources, effectively reducing DNS poisoning risk.

3. Final Answer:

   Use DNSSEC to verify DNS data and configure trusted DNS servers -> Option C

4. Quick Check:

   DNSSEC + trusted DNS = strong DNS poisoning defense [OK]

Hint: Use DNSSEC and trusted servers to stop poisoning [OK]

Common Mistakes:

• Thinking public Wi-Fi is safe
• Manually editing hosts is impractical
• Relying only on antivirus misses DNS attacks