Interview Questions and Answers For DHCP SERVER

1) What is DHCP?

DHCP stands for "Dynamic Host Configuration Protocol".

2) What is DHCP's purpose?

Dhcp server helps to assign ip address to the clients in the network.and also it assign subnet mask ,default gateway and  primary and secondary dns address.The overall purpose of this is to reduce the work necessary to administer a large IP network       

                                                                     

3) What is dhcp scope ?
DHCP scopes are used to define ranges of addresses from which a DHCP server can assign IP addresses to clients.

Eg: 192.168.1.1 to 192.168.1.200

4) What is Exclusion range in dhcp server?

We can exclude some ip range from a active scope which may be assigned to servers

Eg: 192.168.1.1 to 192.168.1.5 this range will be excluded from the scope

5) What is reservation in dhcp server?

In reservation option we can bind a ip address to host using its MAC address. Every time it gets the same ip till the reservation is active

6) Which port does DHCP uses?

UDP port 67 client machine listen over port 68

7) What process dhcp server use and Explain?

Dhcp uses DORA process

D-Discover: A user turns on a computer with a DHCP client. The client computer sends a broadcast request called a DISCOVER message throughout the network, looking for a DHCP server to answer. The router directs the DISCOVER packet or message  to the correct DHCP server. The server receives the DISCOVER packet

O-Offer: As the dhcp receive the request from client, the server determines an appropriate address (if any) to give to the client. The server then temporarily reserves that address for the client and sends back to the client an OFFER packet or message, with that address information

R- Request: The dhcp client will get related request  from all dhcp servers ,and it will accept the first one that it receives.It will then send a request to the DHCP for the offered IP address.
A-Acknowledge: When DHCP received the DHCP Request from the client for the IP address, it will send back a DHCP acknowledge, thereby allocating that IP address to the client

8) If DHCP is not available what happens to the client?

Client will not get IP and it cannot be participated in network . If  client already got the IP and having lease duration it use the IP till the lease duration expires.

9) what is the difference between Authorized DHCP and Non Authorized DHCP?

To avoid problems in the network causing by mis-configured DHCP servers, server in windows 2000 must be validate by AD before starting service to clients. If an authorized DHCP finds any DHCP server in the network it stops serving the clients 

10) What is APIPA IP address?

APIPA stands for automatic private IP addressing. When DHCP server is not available the Windows client computer assigns an automatic IP address to itself so that it can communicate with the network computers. This ip address is called APIPA

11) What IP address is assigned to the computer when the DHCP server is not available?

It’s in the range of 169.254.X.X

12) What protocol and port does DHCP use?

DHCP, like BOOTP runs over UDP, utilizing ports 67 and 68.

13) What is a DHCP lease?

A DHCP lease is the amount of time that the DHCP server permits to the DHCP client to use a particular IP address. Administrator can set the lease time.

14) Can a BOOTP client boot from a DHCP server?

Only if the DHCP client were specifically written to make use of the answer from a BOOTP server.

Can a DHCP server back up another DHCP server?

You can have two or more servers handing out leases for different addresses.

15) Where is DHCP defined?

In Internet RFCs.

16) Benefits of using DHCP ?
Safe and reliable configuration.

DHCP avoids configuration errors caused by the need to manually type in ip address at each computer.

DHCP prevent address conflicts caused by a previously assigned IP address being reused to configure a new computer on the network.