1. What is the primary function of DNS?
Correct Answer: b) Mapping domain names to IP addresses
Explanation: DNS primarily translates human-readable domain names (like example.com) to machine-readable IP addresses (like 192.0.2.1), enabling users to access websites using memorable names.
2. Which DNS record maps a hostname to an IPv4 address?
Correct Answer: c) A
Explanation: The A record (Address record) maps a domain name to an IPv4 address. For IPv6 addresses, AAAA records are used instead.
3. Which DNS record is used for email routing?
Correct Answer: b) MX
Explanation: MX (Mail Exchange) records specify the mail servers responsible for receiving email messages on behalf of a domain, along with their priority values.
4. What is the purpose of a CNAME record?
Correct Answer: a) Maps an alias to a canonical name
Explanation: CNAME (Canonical Name) records create aliases that point to another domain name (the canonical name) rather than directly to an IP address.
5. Which protocol does DNS primarily use?
Correct Answer: b) UDP (Port 53)
Explanation: DNS primarily uses UDP on port 53 for standard queries due to its low overhead. TCP is used for zone transfers or when response data exceeds 512 bytes.
6. What is a DNS resolver?
Correct Answer: b) A client that queries DNS servers
Explanation: A DNS resolver is typically a client (often part of the operating system) that initiates DNS queries on behalf of applications and receives responses from DNS servers.
7. Which DNS server stores records for a specific domain?
Correct Answer: c) Authoritative Server
Explanation: Authoritative name servers contain the actual DNS records for domains and provide definitive answers to queries about those domains.
8. What is DNS caching used for?
Correct Answer: a) Reducing DNS query latency
Explanation: DNS caching stores previous query results locally for a specified time (TTL), reducing the need to repeatedly query authoritative servers and improving response times.
9. Which of the following is a top-level domain (TLD)?
Correct Answer: a) .com
Explanation: TLDs are the highest level of domain names in the DNS hierarchy. .com is a generic TLD (gTLD), while others like .google are brand-specific or reserved for special purposes.
10. What is DNSSEC used for?
Correct Answer: b) Securing DNS with digital signatures
Explanation: DNSSEC (DNS Security Extensions) adds cryptographic signatures to DNS records to authenticate responses and protect against DNS spoofing and cache poisoning attacks.