Introduction
In this article, we are going to see some of the most frequently asked questions in DHCP interviews. To start with, DHCP stands for Dynamic Host Configuration Protocol. DHCP is basically a network management protocol and is used mostly on TCP/IP(Transmission Control Protocol/Internet Protocol) networks.
Being good at DHCP offers you various career opportunities across diverse roles. These roles include Infrastructure developer, Active Directory Administrator, Tech Specialist, and many more. So if you are willing to appear in an interview for DHCP jobs, Coding Ninjas got you covered!

This article focuses on helping you get comfortable with essential questions that will help you to come out with flying colors after your interview. To help you understand better, we have divided this article into three sections: Easy level section, Medium level section, and Hard level section. So let’s get started.
Most Asked DHCP Interview Questions and Answers
This section contains the basic DHCP interview questions and is focused on building a solid foundation. We will go step by step, starting with the easy DHCP interview questions.
1. What is the full form of DHCP?
Ans: The full form of DHCP is Dynamic Host Configuration Protocol.
2. What does DHCP do?
Ans: Dynamic Host Configuration Protocol: Assigns IP addresses to clients on a dynamic or automatic basis.
3. What is the scope of DHCP?
Ans: Scope is basically the range of IP addresses that is assigned to DHCP clients.
4. What do you mean by an IP Lease?
Ans: The DHCP server assigns the client an IP address for a time period of 8 days. We call this offer an IP Lease.
5. What exactly is IP Reservation?
Ans: IP Reservation means reserving a specific dynamic IP address for a certain system. When you use the DHCP IP reservation, you basically instruct your Wi-Fi network to assign the same IP address to a specific device each time it connects to your network.
6. Which ports do DHCP, and the DHCP clients use?
Ans: For requests, UDP Port 68 is used, and for server responses, UDP Port 67 is used.
7. What do you mean by exclusion?
Ans: Exclusion is omitting the assigning that have been previously assigned from the range of selected IPs.
8. What exactly is a SUPER SCOPE?
Ans: A super scope is a group of scopes. For example, if a company wished to handle several network clients or companies with a single router, it might establish a superscope with multiple scopes set with distinct network address spaces.
9. What is the file extension for DHCP Database?
Ans: “.mdb” is the file extension used for the DHCP database.
10. What is the default storage location for the DHCP database?
Ans: ‘SystemrootSystem32Dhcp’ is the DHCP database storage location.
11. What is the goal of DHCP?
Ans: The aim of DHCP is to allow individual computers on an IP network to retrieve their configurations from a server or servers, namely ones that do not hold accurate information about the individual computers until they request it. The final goal is to reduce the amount of effort required to run a big IP network. The IP address is the most important piece of information supplied in this method.
12. What do you mean by DHCP Spoofing?
Ans: Ascend Pipeline ISDN(Integrated Services Digital Network) routers that link Ethernets to ISDN lines include a feature known as "DHCP spoofing", which is basically a small server implementation that hands an IP address to a connecting Windows 95 PC in order to provide it an IP number during the connection process.
13. Is it possible for DHCP to provide statically defined addresses?
Ans: Yes, it is. There is nothing in the protocol that prevents this, and it is expected to be a function of any DHCP server.
This is primarily a server issue, and the client should function in any case. This is referred to as manual allocation in the RFC (Remote Function Call).
14. What is DHCPInform?
Ans: DHCPInform is a DHCP message used by DHCP clients to receive DHCP parameters. On one hand, PPP(Public Private Partnership) remote access clients do not use DHCP to obtain IP addresses for the remote access connection, while Windows 2000 and Windows 98 remote access clients use the DHCPInform message in order to obtain DNS (Domain Name System) server IP addresses, WINS (Windows Internet Name Service) server IP addresses, and a DNS domain name.
15. What is a DHCP relay agent?
Ans: Any host or IP router that forwards DHCP packets between clients and servers is referred to as a DHCP relay agent.
16. What is the IP address of APIPA (Automatic Private IP Addressing)?
Ans: When a DHCP server fails or goes down, the computer automatically assigns an IP address to the client, which is the APIPA IP address.
17. What is the APIPA IP address range?
Ans: 169.254.0.1 - 169.254.255.255 is the assigned range for the APIPA IP address.
18. What do you know about the DHCP decline message?
Ans: The DHCP decline message is sent by the client to the server. It indicates that the network address is already in use, which means it has already been assigned to another device.
19. Can DHCP prevent illegal laptops from connecting to a DHCP-based network?
Ans: No, DHCP is not capable of discriminating between a permanent MAC address and a user-supplied address. As a result, it cannot prevent unwanted network access and cannot manage the IP addresses used by users.
20. Which command is used for releasing an IP address?
Ans: ipconfig /release is the command used for releasing an IP address.
21. What command is used to renew an IP address?
Ans: ipconfig /renew is the command used for renew an IP address.
22. How does DHCP function?
Ans: The DORA(DISCOVER - OFFER - REQUEST - ACKNOWLEDGMENT) process is used by DHCP.
- Discover: The client learns about the DHCP
- Offer: DHCP provides the client with a list of IP addresses from which to pick.
- Request: After selecting an IP address, the client seeks confirmation from DHCP.
- Acknowledgment: DHCP sends a confirmation to the client by sending a DHCP pack.
23. What are the different kinds of Scopes in Windows DHCP?
Ans: Normal Scope - Allows the specification of A, B, and C Class IP address ranges, as well as subnet masks, exclusions, and reservations. Each normal scope specified must have its own subnet.
Multicast Scope- Class D networks use the multicast scope to assign IP address ranges. Subnet masks, reservations, and other TCP/IP settings are not available in multicast scopes.
A Time To Live (TTL) value must be given for multicast scope address ranges.
Superscope - A superscope is technically a group of scopes that can be enabled and disabled as a single entity.
24. In Active Directory Open DHCP, how do you authorize a DHCP server?
Ans: For authorizing a DHCP server in the active directory open DHCP, and follow the given steps:
- Select DHCP from the console tree.
- Select ‘Manage authorized servers’ from the Action menu.
- The dialogue box ‘Manage Authorized Servers’ displays. Click the ‘Authorize’ button.
- When indicated, enter the name or IP address of the approved DHCP server and then click ‘OK’.
25. What Information can a DHCP server give to a host?
Ans: The following information can be obtained from a DHCP server:
- Subnet mask
- IP address
- The default gateway
- WINS(Windows Internet Name Service) information for domain name servers
26. What is the DHCPNAK message?
Ans: A DHCP server sends a DHCP NAK message in response to a DHCP client's DHCP Request message. If a DHCP server cannot find matching lease records after receiving a DHCP Request message, it delivers a DHCP NAK message to the DHCP client, indicating that no IP address is available.
27. What is the relationship between DHCP and DNS?
Ans: DNS and DHCP servers have traditionally been configured and handled one at a time. Changing authorization permissions for a certain user on a set of devices has also required visiting each one and making configuration modifications.
The integration of DHCP and DNS enables the aggregation of these functions across devices, allowing a company's network services to scale in tandem with the development of network users, devices, and rules while lowering administrative operations and costs. This integration results in tangible operational efficiencies that reduce total cost of ownership.
Creating a DHCP network, for example, automatically generates an associated DNS zone, decreasing the number of actions required of network managers.
28. How do DHCP and BOOTP(Bootstrap Protocol) deal with numerous subnets?
Ans: The BOOTP protocol is a TCP/IP protocol. It allows a client to obtain its IP address and the name of a load file from a network server.
There are two approaches for instances where there are several LANs, each with its own subnet number.
- First and foremost, each subnet can have its own server.
- Second, some routers have a capability known as "BOOTP forwarding" that allows them to forward DHCP or BOOTP requests to a server on another subnet and then forward the responses back to the client.
A "BOOTP forwarding agent" is the component of such a router or server functioning as a router that achieves this. Typically, you must activate it on the interface to the subnet to be serviced and configure it with the DHCP or BOOTP server's IP address.
29. Is DHCP compatible with AppleTalk or IPX?
Ans: No, it is excessively dependent on IP. Furthermore, they have always had automatic procedures for assigning their own network addresses. Thus they do not require it.
30. How can I keep unauthorized laptops from accessing a network that uses DHCP for dynamic addressing?
Ans: This would have to be accomplished in a manner other than DHCP. DHCP cannot distinguish between a computer's permanent MAC address and one provided by the computer's user, nor can it prohibit other clients from utilizing the addresses it is configured to distribute. DHCP cannot restrict which IP addresses can use a specific port or manage the IP address used by any client.
31. Is it possible for a DHCP server to serve as a backup for another DHCP server?
Ans: Two or more servers can issue leases for separate addresses. If both servers provide a dynamic pool that is accessible to the same clients, even if one server is offline, one of those clients can lease an address from the other.
However, without communication between the two servers to share information on current leases, when one server goes down, any client who has a lease with that server will be unable to extend their lease with the other server.
The "server-to-server protocol" is designed to facilitate such communication. Some server suppliers may have addressed this issue through their own proprietary server-to-server communication.
