Top 18 DNS Interview Questions and Answers

Q1: What is DNS?

Ans: DNS stand for Domain Name System/Service. It’s used to resolve FQDN (Fully qualified domain name) to IP address and Vice versa such as www.example.com to 184.59.51.27 and vice versa.

Q2: How many types of DNS?

Ans:  There are two types of DNS server:

Q3: How many types of zone in DNS?

Ans: There are three types of Zone in DNS:

Q4: What is stub zone?

Ans: Stub zone contains Name Server record, SOA and SRV information of network which helps to resolve fast query and assign best path.

Q5: What is Secondary zone and how does it different from primary zone?

Ans: Secondary zone is copy of primary zone, it’s contain read only database of primary zone whereas primary zone contains main database of DNS Server. when primary zone fail to respond then secondary zone resolve client query. It’s means fault tolerance also.

Q6: How many lookup zone in DNS?

Ans: There are two lookup zone in DNS:

Q7: What is forward lookup zone?

Ans: Forward lookup zone helps to resolve name (www.example.com) to IP address (61.95.235.79). A record creates in forward lookup zone.

Q8: What is Reverse lookup zone?

Ans: Reverse lookup zone helps to resolve IP Address (104.211.37.48) to name (www.example.com). PTR record creates in Reverse Lookup Zone.

Q9: How many records in DNS server?

Ans:  There are six records in DNS Server:

Q10: What is A record?

Ans: A record is used to resolve Name (www.example.com) to IP Address (61.95.234.98). It creates in Forward lookup zone.

Q11: What is difference between A record and AAAA record?

Ans:  A record called as host record also. It is used to resolve Name to IP Address in IPv4 Address while AAAA record same work but it use in IPv6 Address.

Q12: What is PTR record?

Ans: PTR stand for Pointer record. It is used to resolve IP Address to name like www.example.com to 61.95.125.45. It creates in Reverse lookup zone.

Q13: What is SOA?

Ans:  SOA stand for Start of Authority record. It record is information of DNS zone about that zone and about other zone. Each zone contains single SOA record.

Q14: What is SRV record?

Ans: SRV stand for Service locator record. It contains of all service information of DNS Server like port, target, priority and so on.  

Q15: What is CName/ Alias record?

Ans: Canonical Name/Alias record is used to specify that a domain name is an alias for another domain such as host name test.example.com alias name www.example.com.

Q16: What is MX record?

Ans: Mx stand for Mail Exchanger record. This record use in mail server and responsible for accepting email messages on behalf of recipient’s domain.

Q17: Which port is used by DNS server?

Ans: Port: 53

Q18: What is the Name server and how to identify it?

Ans: Nameserver is a server on the internet to handle queries regarding the location of a domain name's various services. They allow using domains instead of IP addresses.

Q19: What is Round Robin DNS?

Ans: Round Robin DNS is technique which used to load distribution, load balancing or fault-tolerance Internet protocol service host like FTP server, webserver and manage the DNS response to address requests from client computers.