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DNS interview questions

57 DNS questions from the Networking bank, written for Indian campus drives and tech interviews. Every question has a verified answer and an AI-tutor explanation on placd.

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1. What is DNS?

Junior
  1. A.the system that resolves human-readable domain names into IP addresses
  2. B.the bulk copy of zone records from a primary to a secondary name server
  3. C.caching that a name does not exist to avoid repeated failed lookups
  4. D.a DNS record mapping a hostname to an IPv6 address

Answer + AI explanation with Pro

2. Which term means: "the system that resolves human-readable domain names into IP addresses"?

Junior
  1. A.Authoritative name server
  2. B.NS record
  3. C.DNS
  4. D.DNSSEC

Answer + AI explanation with Pro

3. Which statement is correct?

Junior
  1. A.DNS — the well-known port DNS uses, over UDP for queries and TCP for zone transfers
  2. B.DNS — the server that holds the definitive records for a DNS zone
  3. C.DNS — encrypting DNS queries inside HTTPS to protect privacy from on-path observers
  4. D.DNS — the system that resolves human-readable domain names into IP addresses

Answer + AI explanation with Pro

4. What is A record?

Junior
  1. A.a DNS record mapping a hostname to an IPv4 address
  2. B.a DNS record mapping a hostname to an IPv6 address
  3. C.a DNS record that aliases one name to another canonical name
  4. D.a DNS record delegating a zone to its authoritative name servers

Answer + AI explanation with Pro

5. Which term means: "a DNS record mapping a hostname to an IPv4 address"?

Junior
  1. A.PTR record
  2. B.TTL (DNS)
  3. C.DNS over HTTPS (DoH)
  4. D.A record

Answer + AI explanation with Pro

6. Which statement is correct?

Junior
  1. A.A record — a DNS record mapping a hostname to an IPv4 address
  2. B.A record — a DNS record that aliases one name to another canonical name
  3. C.A record — the server that holds the definitive records for a DNS zone
  4. D.A record — a DNS record holding arbitrary text, often used for SPF and domain verification

Answer + AI explanation with Pro

7. What is AAAA record?

Junior
  1. A.a DNS record mapping a hostname to an IPv6 address
  2. B.a DNS record delegating a zone to its authoritative name servers
  3. C.a DNS record mapping an IP address back to a hostname for reverse lookups
  4. D.a DNS record holding arbitrary text, often used for SPF and domain verification

Answer + AI explanation with Pro

8. Which term means: "a DNS record mapping a hostname to an IPv6 address"?

Junior
  1. A.DNS
  2. B.DNS zone transfer (AXFR)
  3. C.AAAA record
  4. D.Negative caching

Answer + AI explanation with Pro

9. Which statement is correct?

Junior
  1. A.AAAA record — caching that a name does not exist to avoid repeated failed lookups
  2. B.AAAA record — a DNS record mapping a hostname to an IPv6 address
  3. C.AAAA record — returning different answers to internal versus external clients for the same name
  4. D.AAAA record — a DNS record holding arbitrary text, often used for SPF and domain verification

Answer + AI explanation with Pro

10. What is CNAME record?

Junior
  1. A.a DNS record that aliases one name to another canonical name
  2. B.returning different answers to internal versus external clients for the same name
  3. C.the Start of Authority record holding zone metadata like serial and refresh timers
  4. D.the system that resolves human-readable domain names into IP addresses

Answer + AI explanation with Pro

11. Which term means: "a DNS record that aliases one name to another canonical name"?

Junior
  1. A.Authoritative name server
  2. B.NS record
  3. C.SOA record
  4. D.CNAME record

Answer + AI explanation with Pro

12. Which statement is correct?

Junior
  1. A.CNAME record — returning different answers to internal versus external clients for the same name
  2. B.CNAME record — a DNS record holding arbitrary text, often used for SPF and domain verification
  3. C.CNAME record — a DNS record that aliases one name to another canonical name
  4. D.CNAME record — a DNS record specifying the mail servers responsible for a domain

Answer + AI explanation with Pro

13. What is MX record?

Junior
  1. A.caching that a name does not exist to avoid repeated failed lookups
  2. B.a DNS server that fully resolves a query on a client's behalf by querying others
  3. C.a DNS record specifying the mail servers responsible for a domain
  4. D.the Start of Authority record holding zone metadata like serial and refresh timers

Answer + AI explanation with Pro

14. Which term means: "a DNS record specifying the mail servers responsible for a domain"?

Junior
  1. A.NS record
  2. B.MX record
  3. C.DNSSEC
  4. D.TXT record

Answer + AI explanation with Pro

15. Which statement is correct?

Junior
  1. A.MX record — the system that resolves human-readable domain names into IP addresses
  2. B.MX record — the Start of Authority record holding zone metadata like serial and refresh timers
  3. C.MX record — a DNS record specifying the mail servers responsible for a domain
  4. D.MX record — caching that a name does not exist to avoid repeated failed lookups

Answer + AI explanation with Pro

16. What is port 53 → DNS?

Junior
  1. A.the Start of Authority record holding zone metadata like serial and refresh timers
  2. B.returning different answers to internal versus external clients for the same name
  3. C.the bulk copy of zone records from a primary to a secondary name server
  4. D.the well-known port DNS uses, over UDP for queries and TCP for zone transfers

Answer + AI explanation with Pro

17. Which term means: "the well-known port DNS uses, over UDP for queries and TCP for zone transfers"?

Junior
  1. A.TXT record
  2. B.DNS
  3. C.Negative caching
  4. D.port 53 → DNS

Answer + AI explanation with Pro

18. Which statement is correct?

Junior
  1. A.port 53 → DNS — caching that a name does not exist to avoid repeated failed lookups
  2. B.port 53 → DNS — the system that resolves human-readable domain names into IP addresses
  3. C.port 53 → DNS — the well-known port DNS uses, over UDP for queries and TCP for zone transfers
  4. D.port 53 → DNS — extensions that cryptographically sign DNS records to prevent spoofing and cache poisoning

Answer + AI explanation with Pro

19. What is Recursive resolver?

Mid
  1. A.a DNS record delegating a zone to its authoritative name servers
  2. B.a DNS server that fully resolves a query on a client's behalf by querying others
  3. C.caching that a name does not exist to avoid repeated failed lookups
  4. D.a DNS record that aliases one name to another canonical name

Answer + AI explanation with Pro

20. Which term means: "a DNS server that fully resolves a query on a client's behalf by querying others"?

Mid
  1. A.NS record
  2. B.A record
  3. C.AAAA record
  4. D.Recursive resolver

Answer + AI explanation with Pro

21. Which statement is correct?

Mid
  1. A.Recursive resolver — a DNS server that fully resolves a query on a client's behalf by querying others
  2. B.Recursive resolver — a DNS record mapping a hostname to an IPv4 address
  3. C.Recursive resolver — a DNS record delegating a zone to its authoritative name servers
  4. D.Recursive resolver — caching that a name does not exist to avoid repeated failed lookups

Answer + AI explanation with Pro

22. What is Authoritative name server?

Mid
  1. A.a DNS record holding arbitrary text, often used for SPF and domain verification
  2. B.extensions that cryptographically sign DNS records to prevent spoofing and cache poisoning
  3. C.the server that holds the definitive records for a DNS zone
  4. D.a DNS record delegating a zone to its authoritative name servers

Answer + AI explanation with Pro

23. Which term means: "the server that holds the definitive records for a DNS zone"?

Mid
  1. A.Authoritative name server
  2. B.CNAME record
  3. C.NS record
  4. D.A record

Answer + AI explanation with Pro

24. Which statement is correct?

Mid
  1. A.Authoritative name server — a DNS record specifying the mail servers responsible for a domain
  2. B.Authoritative name server — the well-known port DNS uses, over UDP for queries and TCP for zone transfers
  3. C.Authoritative name server — a DNS record mapping an IP address back to a hostname for reverse lookups
  4. D.Authoritative name server — the server that holds the definitive records for a DNS zone

Answer + AI explanation with Pro

25. What is TTL (DNS)?

Mid
  1. A.the Start of Authority record holding zone metadata like serial and refresh timers
  2. B.extensions that cryptographically sign DNS records to prevent spoofing and cache poisoning
  3. C.the time in seconds a DNS record may be cached before re-querying
  4. D.a DNS record specifying the mail servers responsible for a domain

Answer + AI explanation with Pro

26. Which term means: "the time in seconds a DNS record may be cached before re-querying"?

Mid
  1. A.PTR record
  2. B.CNAME record
  3. C.Authoritative name server
  4. D.TTL (DNS)

Answer + AI explanation with Pro

27. Which statement is correct?

Mid
  1. A.TTL (DNS) — the time in seconds a DNS record may be cached before re-querying
  2. B.TTL (DNS) — a DNS server that fully resolves a query on a client's behalf by querying others
  3. C.TTL (DNS) — a DNS record holding arbitrary text, often used for SPF and domain verification
  4. D.TTL (DNS) — extensions that cryptographically sign DNS records to prevent spoofing and cache poisoning

Answer + AI explanation with Pro

28. What is PTR record?

Mid
  1. A.a DNS record mapping a hostname to an IPv4 address
  2. B.the server that holds the definitive records for a DNS zone
  3. C.a DNS record that aliases one name to another canonical name
  4. D.a DNS record mapping an IP address back to a hostname for reverse lookups

Answer + AI explanation with Pro

29. Which term means: "a DNS record mapping an IP address back to a hostname for reverse lookups"?

Mid
  1. A.DNS
  2. B.MX record
  3. C.PTR record
  4. D.NS record

Answer + AI explanation with Pro

30. Which statement is correct?

Mid
  1. A.PTR record — the system that resolves human-readable domain names into IP addresses
  2. B.PTR record — a DNS record mapping a hostname to an IPv6 address
  3. C.PTR record — a DNS record mapping an IP address back to a hostname for reverse lookups
  4. D.PTR record — the server that holds the definitive records for a DNS zone

Answer + AI explanation with Pro

Showing 30 of 57 DNS questions — the full set, with answers, explanations and an AI tutor on every question, is inside.

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