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Table of contents
1.
Introduction
2.
What is DNS?
3.
DNS Interview Questions for Freshers
3.1.
1. What is DNS?
3.2.
2. What is TTL, and what is suitable TTL for your DNS?
3.3.
3. What is the 224.0.1.24 address used for?
3.4.
4. What is static and dynamic DNS record?
3.5.
5. What is DDNS?
3.6.
6. What is the main purpose of SRV records?
3.7.
7. What is Caching Only Server?
3.8.
8. Which TCP/IP port is used by the DNS server?
3.9.
9. How will you check the status of DNS online?
3.10.
10. What Is Authoritative Name-Server?
3.11.
11. What is a recursive DNS resolver?
3.12.
12. What Is a primary Zone?
3.13.
13. What is a secondary zone?
3.14.
14. What is a stub zone?
4.
DNS Interview Questions for Experienced
4.1.
15. What is a DNS server?
4.2.
16. What is Forwarder (DNS Server)?
4.3.
17. What are forward and reverse lookup?
4.4.
18. What is the Authoritative DNS server?
4.5.
19. Why do we Use DNS?
4.6.
20. What is the role of UDRP?
4.7.
21. What are the main functions of Domain Names?
4.8.
22. What is the purpose of Domain Name Spacing?
4.9.
23. Soa Records Must Be Included In Every Zone. What Are They Used For?
4.10.
24. What is DNS spoofing?
4.11.
25. What is round-robin DNS?
4.12.
26. What are SRV records? Name all the types of SRV records.
4.13.
27. What are resource records in DNS?
5.
Frequently Asked Questions
5.1.
What are the three types of DNS?
5.2.
What is the main role of a DNS?
5.3.
What are the four types of DNS servers?
6.
Conclusion
Last Updated: Mar 27, 2024
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DNS Interview Questions and Answers

Author soham Medewar
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Introduction

Internet domain names are located and converted into internet protocol (IP) addresses using the domain name system. The IP address that a computer uses to discover a website is mapped to the name that people use to find a website through the domain name system.

dns interview questions

The notion of the Domain Name System (DNS) is crucial to networking. We will be covering the most important DNS interview questions and answers.

What is DNS?

DNS stands for Domain Name System. It is a hierarchical and decentralized naming system for computers, services, or other resources connected to the Internet or a private network. The DNS system associates various information with domain names assigned to each of the participating entities, such as IP addresses or mail server information. 

When a user types a domain name into their web browser or sends an email, the DNS translates the domain name into the corresponding IP address or mail server address so that the request can be sent to the appropriate server. DNS also supports the creation of subdomains, email routing, and other domain-related functionalities.

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DNS Interview Questions for Freshers

1. What is DNS?

The term "domain name system" is an acronym for DNS. DNS links domain names to the IP addresses of the devices or websites that these domains relate to. The complete internet address is made simple to remember by using DNS to translate the IP address into the domain name. Since IP addresses are used for every communication in networks, it might be challenging to remember them for every website. Instead of using IP addresses to visit websites, we use their domain names on the internet. For instance, you may reach various websites like "google.com" or "youtube.com" by their domain names rather than IP addresses since DNS converts domain names to IP addresses on the backend and makes it available for us.

What is DNS?

2. What is TTL, and what is suitable TTL for your DNS?

"Time to Live" is referred to as TTL. DNS TTL refers to the period of time that a resolver is expected to cache a DNS query for each DNS record specified before the query expires, and a new one must be made. If you don't need to make DNS changes, a recommended TTL of 24 hours is usually sufficient. However, if you intend to modify a DNS record, you can set a lower TTL value between 1 and 5 minutes at least 24 hours beforehand.

3. What is the 224.0.1.24 address used for?

224.0.1.24 is a group address for a WINS server. It s Supports automatic discovery and dynamic replication setup for WINS servers.

4. What is static and dynamic DNS record?

Static DNS records are manually constructed DNS entries, and an A Static IP address points to your domain name on the Internet. In contrast, users of Dynamic DNS can set up automatic updates to their DNS records.

5. What is DDNS?

A Domain Name System (DNS) can be updated in real-time to refer to an altering IP address on the Internet using a technique called dynamic DNS (DDNS). This is used to provide a resource that could move throughout the network as a persistent domain name.

what is ddns

6. What is the main purpose of SRV records?

In order to identify hosts that deliver certain network services, SRV records are employed.

7. What is Caching Only Server?

DNS servers that simply process name resolution requests, cache the responses, and then provide the results to the client are known as caching-only servers. When a query is cached, the next time, it can be resolved locally rather than visiting the real site.

caching server

8. Which TCP/IP port is used by the DNS server?

For zone transfers and maintaining coherence between DN-database and DNS server, DNS servers use port 53.

9. How will you check the status of DNS online?

A variety of utilities are available, including NSLOOKUP, DNSCMD, DNS Console, IPCONFIG, and DNS Logs. Additionally, these DNS utilities are accessible online on many websites.

10. What Is Authoritative Name-Server?

An authoritative name server responds to queries and is set up by an original source. An authoritative name server only responds to queries regarding domain names that the administrator has specifically specified. The authoritative name server is the final owner of the domain's IP address.

11. What is a recursive DNS resolver?

An intermediary server called the recursive DNS resolver delivers the domain's IP address from the authoritative DNS servers. Any DNS query on the internet first goes to Recursive DNS RESOLVER. The Recursive server spends time locating DNS records when a client requests a DNS query.

12. What Is a primary Zone?

This is a zone file in the DNS namespace that may be read and written to. It holds the master copy of zone data in a local file or in AD DS, and it is the main source of information about the zone. zone_name.dns is the default name of the principal zone file, which is located in the server's /windir/System32DNS subdirectory.

13. What is a secondary zone?

This zone file in the DNS namespace is a read-only copy. This is a secondary source for zone information, and it receives the most recent information from the principal zone's master copy. It is necessary to have network connectivity in order to connect to the main server. Secondary zones cannot be kept in AD DS since they are just copies of primary zones that are hosted on other servers.

DNS zones

14. What is a stub zone?

A stub zone is a read-only duplicate of a zone that only contains the resource entries required to identify the zone's authoritative DNS servers. In reality, names are resolved between several DNS namespaces via stub zones. This kind of zone is typically produced when two corporate namespaces combine or are acquired, and DNS servers from those namespaces resolve client names.

A stub zone includes:

  • A master server's IP address may be used to update the stub zone.
     
  • The glue A resource records, name server resource records, and the start of authority (SOA) resource records for the delegated zone.

DNS Interview Questions for Experienced

15. What is a DNS server?

On the internet, a DNS server is a computer system that stores a database of public IP addresses and the domain names that go with them. As required, the DNS server resolves or converts the IP addresses into hostnames. The primary function of a DNS server is to locate and provide webpages to end users on the Internet or a private network. It is constantly linked to a network or the Internet. DNS servers use unique protocols and run specialized software to connect with one another.

16. What is Forwarder (DNS Server)?

If the primary DNS server cannot answer the query, the forwarder DNS server takes care of it. In this scenario, queries are routed to another DNS server that has been set up as a forwarder DNS server.

17. What are forward and reverse lookup?

Forward Lookup: In general, a forward lookup occurs when a name query is sent to the DNS server against an IP address.

Reverse Lookup: DNS also has a reverse lookup procedure that enables clients to search for a computer name based on an address by using a known IP address during a name query.

18. What is the Authoritative DNS server?

A DNS server that originally stores DNS records and resources is the authoritative server. The resource record that was requested will be returned by this server, which is at the end of the DNS lookup chain. An authoritative DNS server finally allows the web browser to make the query to reach the IP address required to access a website.

19. Why do we Use DNS?

  • The location of websites on the internet can be accessed via DNS.
     
  • DNS gives a website a special IP address and enables it to be uniquely identified.
     
  • By using domain name systems, users may visit websites by just typing in the name rather than the IP address.

20. What is the role of UDRP?

  • The Uniform Domain Name Dispute Resolution Policy (UDRP) is provided by the Internet Corporation for Assigned Names and Numbers (ICANN).
     
  • The UDRP makes recommendations and relies on WIPO reports. In this manner, the report is examined, and appropriate measures are performed.
     
  • The WIPO Report on the Internet Domain Name Process contains information about disputes and difficulties.
     
  • The UDRP provides a mechanism for reporting difficulties or conflicts that may arise between trademarks and domain names.
     
  • The reports generated can be identified using the First WIPO Process, and they can be addressed further in additional alternate port domains.
role of UDRP

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21. What are the main functions of Domain Names?

  • Using domain names, users of Internet resources with numerical addresses may quickly recognize and remember the names.
     
  • It serves as a means of addressing Internet resources that have been placed online, or it offers an abstraction that enables the movement of resources from one place to another in the hierarchy.
     
  • It offers a method for topological resource movement and allows translation to be carried out using IP addresses and domain names.
     
  • Domain names give registrants a means to refer to the domain owners who are in charge of the domain's registration and ownership.

22. What is the purpose of Domain Name Spacing?

  • The Internet Corporation for Assigned Names and Numbers, or ICANN, offers tools for managing the hierarchy.
     
  • The top-level domains that are being created or are in the process of being created are part of its management.
     
  • Its architecture was developed utilizing the Internet domain name space since this enables authorization from registrars.
     
  • The domain name space is necessary to enable file hosting and simple portal management.
     
  • It enables the domain name servers' served zones to be arranged and maintained in a hierarchical manner.

23. Soa Records Must Be Included In Every Zone. What Are They Used For?

All resource records in the zone automatically use the TTL value included in SOA records. SOA records include the e-mail address of the person who is responsible for maintaining the zone.   The zone's current serial number, which is utilized in zone transfers, can be found in SOA records.

24. What is DNS spoofing?

In a DNS spoofing attack, the attacker modifies the DNS records and directs online traffic to a phoney website that closely matches the one to which it is being sent. Once a person enters the site, it might prompt them to check in (look like their website), providing the hacker with the opportunity to steal their login information and other kinds of private information. These dangerous websites are frequently used to infect a user's computer with viruses and grant the hacker long-term access to the computer.

25. What is round-robin DNS?

For the purpose of distributing the load of DNS requests made against a domain name, round-robin DNS is utilized.

Assume we have the domain codingninjas.com, which is set up with Round Robin DNS and has two IP addresses mapped to it, as shown below:

codingninjas.com 12.13.27.1

codingninjas.com 12.13.27.2

The first DNS request will go to 12.13.27.1, and the second goes to 12.13.27.2.

26. What are SRV records? Name all the types of SRV records.

The six service records are referred to as SRVs. They can be used to find the services.

types of SRV records
  • MSDCS: Contains DCs information.
     
  • TCP: Contains Global Catalog, Kerberos & LDAP information.
     
  • UDP: Contains Sites information.
     
  • Sites: Contains Sites information.
     
  • Domain DNS Zone: Conations domain's DNS-specific information.
     
  • Forest DNS zone: Contains Forest's Specific Information.

27. What are resource records in DNS?

  • A (Address) relates an IP address to a hostname. A machine should have numerous address records if it has multiple adapter cards and IP addresses.
     
  • A host name's alias is set using CNAME (Canonical Name). For instance, zeta.tvpress.com may have www.tvpress.com as an alias utilizing this record.
     
  • Mail may be delivered to the appropriate mail servers in the domain thanks to the MX (Mail Exchange) setting, which designates a mail exchange server for the domain.
     
  • A name server is specified in the NS (Name Server) field for the domain to enable DNS lookups across several zones. This record should declare each primary and secondary name server.
     
  • PTR (Pointer) generates a pointer for reverse lookups that associates an IP address with a hostname.
     
  • The server designated as the SOA (Start of Authority) is the best source of DNS information for the zone and is thus the most authoritative host for the zone. There must be an SOA entry in each zone file (which is created automatically when you add a zone).

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Frequently Asked Questions

What are the three types of DNS?

The three types of DNS are recursive resolver, authoritative nameserver, and root nameserver. Recursive resolvers fetch DNS information on a client's behalf. Authoritative nameservers store DNS records for specific domains, and root nameservers provide the starting point for DNS resolution.

What is the main role of a DNS?

The main role of a DNS is to translate human-readable domain names into machine-readable IP addresses, allowing devices to locate and communicate with each other on the internet. DNS also supports other important functions like email routing and network configuration.

What are the four types of DNS servers?

The four types of DNS servers are recursive resolver, root nameserver, TLD (Top-Level Domain) nameserver, and authoritative nameserver. Recursive resolver servers fetch DNS information on behalf of a client, root nameservers provide the starting point for DNS resolution, TLD nameservers manage top-level domain information, and authoritative nameservers store DNS records for specific domains.

Conclusion

In this article, we walked through all the important DNS interview questions, from basic to experienced. That's it from the article. I hope you all find it useful.

After reading the above DNS interview questions, you can also refer to interview questions in domains like oops interview questionsSQL interview questionsAEM interview questions, and many more. Nevertheless, you may consider our paid courses to give your career an edge over others!

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