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Domain Name System (DNS)

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The Domain Name System (DNS) is a hierarchical, distributed database that translates human-readable domain names (e.g., www.example.com) into their corresponding Internet Protocol (IP) addresses. This allows users to access websites or other network resources using easily-remembered domain names in…

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CompTIA Network+ - Domain Name System (DNS) Example Questions

Test your knowledge of Domain Name System (DNS)

Question 1

While troubleshooting a server, a network technician determines that the issue is related to an incorrect DNS record. The technician resolves the problem and wants to verify the fix as quickly as possible. What command should the technician use to clear the DNS resolver cache?

Correct Answer: ipconfig /flushdns

The correct command to use in order to clear the DNS resolver cache is 'ipconfig /flushdns'. This command is used to clear the DNS resolver cache when troubleshooting DNS issues, which can help the changes or fixes to take effect more quickly. The command 'ipconfig /renew' is incorrectly listed as it is used to renew the DHCP configuration for all adapters, not to clear the DNS cache. The command 'ipconfig /registerdns' also doesn't fit here because it is used to manually force a refresh of the DNS names that a computer is registered with, not to clear the cache. Lastly, 'ipconfig /release' is incorrect since it is used to release the DHCP lease, not to deal with DNS issues.

Question 2

A network administrator is tasked to create an alias for the company's file server in the DNS, which will also handle printer services. What record should the administrator create?

Correct Answer: CNAME record

The CNAME record is used to create an alias for a hostname. In this question, the network administrator is looking to create an alias for the company's file server in the DNS, which also handles printer services, hence a CNAME record is the appropriate choice. An A record, on the other hand, is used to translate hostnames to IP addresses, not to create aliases. A PTR record is used for the reverse of an A record i.e., to get the hostname corresponding to an IP address. An MX record is used specifically for mail exchange servers. None of these other record types serve the purpose described in the question.

Question 3

A network administrator has enabled DNSSEC for an organization in order to prevent security threats. Which security benefit does DNSSEC offer?

Correct Answer: Protects against DNS cache poisoning

DNSSEC, short for Domain Name System Security Extensions, specifically secures the integrity of DNS messages by using digital signatures. This primarily protects against DNS cache poisoning, a security threat where corrupted DNS data is introduced into a DNS resolver's cache, causing the resolver to return an incorrect IP address and redirect traffic to an attacker's computer. The other answers are incorrect because DNSSEC does not directly prevent DDoS attacks or secure data packets between endpoints. While it does provide authentication, making unauthorized zone transfers more difficult, its primary purpose and security benefit is to protect against DNS cache poisoning.

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