Ans: Dynamic Host Configuration Protocol (DHCP) is a client/server protocol that automatically provides an Internet Protocol (IP) host with its IP address and other related configuration information such as the subnet mask and default gateway. RFCs 2131 and 2132 define DHCP as an Internet Engineering Task Force (IETF) standard based on Bootstrap Protocol (BOOTP), a protocol with which DHCP shares many implementation details. DHCP allows hosts to obtain necessary TCP/IP configuration information from a DHCP server.
The Microsoft Windows Server 2003 operating system includes a DHCP Server service, which is an optional networking component. All Windows-based clients include the DHCP client as part of TCP/IP, including Windows Server 2003, Microsoft Windows XP, Windows 2000, Windows NT 4.0, Windows Millennium Edition (Windows Me), and Windows 98.
Q 2.What is the benefits of DHCP?
Ans: In Windows Server 2003, the DHCP Server service provides the following benefits:
Reliable IP address configuration. DHCP minimizes configuration errors caused by manual IP address configuration, such as typographical errors, or address conflicts caused by the assignment of an IP address to more than one computer at the same time.
Reduced network administration. DHCP includes the following features to reduce network administration:
· Centralized and automated TCP/IP configuration.
· The ability to define TCP/IP configurations from a central location.
· The ability to assign a full range of additional TCP/IP configuration values by means of DHCP options.
· The efficient handling of IP address changes for clients that must be updated frequently, such as those for portable computers that move to different locations on a wireless network.
· The forwarding of initial DHCP messages by using a DHCP relay agent, thus eliminating the need to have a DHCP server on every subnet.
Q 3.Why use DHCP
Ans: Every device on a TCP/IP-based network must have a unique unicast IP address to access the network and its resources. Without DHCP, IP addresses must be configured manually for new computers or computers that are moved from one subnet to another, and manually reclaimed for computers that are removed from the network.
DHCP enables this entire process to be automated and managed centrally. The DHCP server maintains a pool of IP addresses and leases an address to any DHCP-enabled client when it starts up on the network. Because the IP addresses are dynamic (leased) rather than static (permanently assigned), addresses no longer in use are automatically returned to the pool for reallocation.
The network administrator establishes DHCP servers that maintain TCP/IP configuration information and provide address configuration to DHCP-enabled clients in the form of a lease offer. The DHCP server stores the configuration information in a database, which includes:
Valid TCP/IP configuration parameters for all clients on the network.
Valid IP addresses, maintained in a pool for assignment to clients, as well as excluded addresses.
Reserved IP addresses associated with particular DHCP clients. This allows consistent assignment of a single IP address to a single DHCP client.
The lease duration, or the length of time for which the IP address can be used before a lease renewal is required.
A DHCP-enabled client, upon accepting a lease offer, receives:
A valid IP address for the subnet to which it is connecting.
Requested DHCP options, which are additional parameters that a DHCP server is configured to assign to clients. Some examples of DHCP options are Router (default gateway), DNS Servers, and DNS Domain Name. For a full list of DHCP options, see “DHCP Tools and Settings.”
Q 4. What is a DHCP server?
Ans: A computer running the DHCP Server service that holds information about available IP addresses and related configuration information as defined by the DHCP administrator and responds to requests from DHCP clients.
Q 5. What is DHCP client?
Ans: A computer that gets its IP configuration information by using DHCP.
Q 6. What is Scope?
Ans: A range of IP addresses that are available to be leased to DHCP clients by the DHCP Server service.
Q 7. What do mean by Lease?
Ans: The length of time for which a DHCP client can use a DHCP-assigned IP address configuration.
Q 8. What do mean by Reservation?
Ans: A specific IP address within a scope permanently set aside for leased use by a specific DHCP client. Client reservations are made in the DHCP database using the DHCP snap-in and are based on a unique client device identifier for each reserved entry.
Q 9. What is BOOTP protocol?
Ans: An older protocol with similar functionality; DHCP is based on BOOTP. BOOTP is an established protocol standard used for configuring IP hosts. BOOTP was originally designed to enable boot configuration for diskless workstations. Most DHCP servers, including those running Windows Server 2003, can be configured to respond to both BOOTP requests and DHCP requests.
Q 10. What is the benefit of using the DHCP?
Ans: DHCP allows for reliable assignment of IP addresses in a network by reducing the need to manually assign addresses to each host. This prevents IP conflicts that can disable a network.
Mobile users receive much of the benefit of DHCP, which allows them to travel anywhere on the intranetwork and automatically receive IP addresses when they reconnect to the network.
Interoperability with DNS servers provides name resolution for network resources, allowing DHCP servers and DHCP clients to register with DNS.
Q 11. What is the drawback of using DHCP?
Ans: Your machine name does not change when you get a new IP address. The DNS (Domain Name System) name is associated with your IP address and therefore does change. This only presents a problem if other clients try to access your machine by its DNS name.
Q 12. What ports are used by DHCP and the DHCP clients?
Ans: DHCP server uses port no. 68 and DHCP clients uses port no. 67.
Q 13. What are the LMHOSTS files?
Ans: The LMHOSTS file is a static method of resolving NetBIOS names to IP addresses in the same way that the HOSTS file is a static method of resolving domain names into IP addresses. An LMHOSTS file is a text file that maps NetBIOS names to IP addresses; it must be manually configured and updated.
Q 14. What is DHCPINFORM?
Ans: DHCPInform is a DHCP message used by DHCP clients to obtain DHCP options. While PPP remote access clients do not use DHCP to obtain IP addresses for the remote access connection, Windows 2000 and Windows 98 remote access clients use the DHCPInform message to obtain DNS server IP addresses, WINS server IP addresses, and a DNS domain name. The DHCPInform message is sent after the IPCP negotiation is concluded.
The DHCPInform message received by the remote access server is then forwarded to a DHCP server. The remote access server forwards DHCPInform messages only if it has been configured with the DHCP Relay Agent..
Q 15. What options in DHCP do you regularly use for an MS network?
Ans: The options are:
Automatic providing IP address
Subnet mask
DNS server
Domain name
Default getaway or router
Q 16. What are user classes and vendor classes in DHCP?
Ans:
Q 17. Describe the integration between DHCP and DNS?
Ans: With Windows Server 2003 Active Directory, Domain Name System (DNS) is the main name resolution method used to provide clients with name to IP address resolution. This in turn enables clients to locate resources on the network. The Dynamic DNS (DDNS) feature, initially introduced in Windows 2000, enables clients to automatically register their IP addresses and host names with a DNS server. When the DHCP service is running on a server, the DHCP server register the IP address of clients in DNS when the clients receive IP addresses from the DHCP server. The client no longer contacts the DDNS server to register its IP addresses because the Windows Server 2003 DHCP service dynamically updates the DNS records on behalf the client.
With Windows Server 2003 DHCP, three options are available for registering IP addresses in DNS. The options can be configured for the DHCP server, or for each individual scope.
The options which can be specified to enable/disable the DHCP service to dynamically update DNS records on behalf the client are:
The DHCP server can be configured to not register any IP address of the DHCP clients when it assigns IP addresses to these clients.
The DHCP server can be configured to at all times register all IP address of clients when they receive IP addresses from the DHCP server.
The default option results in the DHCP server registering the IP addresses of clients with the authoritative DNS server, based on the client.s request for an IP address.
Q 18. How to authorize the DHCP server in Active Directory?
Ans: To authorize the DHCP server in Active Directory
Click Start, All Programs, Administrative Tools and then click DHCP to open the DHCP console.
In the console tree, expand the DHCP server node.
Click the DHCP server that you want to authorize.
Click the Action menu, and then select Authorize.
After waiting for approximately 45 minutes for the authorization to occur, right-click the DHCP server, and verify that Unauthorize is displayed on the shortcut menu.
Q 19. Describe the process of installing DHCP server in an AD infrastructure?
Ans:You can install DHCP either during or after the initial installation of Windows 2000 Server or Advanced Server, although there must be a working DNS in the environment. To validate your DNS server, click Start, click Run, type cmd, press ENTER, type ping friendly name of an existing DNS server in your environment, and then press ENTER. An unsuccessful reply generates an "Unknown Host My DNS server name" message.To install the DHCP Service on an existing Windows 2000 Server:
Click Start, click Settings, and then click Control Panel.
Double-click Add/Remove Programs, and then click Add/Remove Windows Components.
In the Windows Component Wizard, click Networking Services in the Components box, and then click Details.
Click to select the Dynamic Host Configuration Protocol (DHCP) check box if it is not already selected, and then click OK.
In the Windows Components Wizard, click Next to start Windows 2000 Setup. Insert the Windows 2000 Advanced Server CD-ROM into the CD-ROM drive if you are prompted to do so. Setup copies the DHCP server and tool files to your computer.
When Setup is complete, click Finish.
Q 20. Describe the steps taken by the client and DHCP server in order to obtain an IP address?
Ans: The process of acquiring an IP address is described here:
Step 1 The client workstation boots and initializes with a "null IP address" that lets it communicate with the DHCP server using TCP/IP. It prepares a message that contains its MAC address (for example, the hardwired address of its Ethernet adapter) and its computer name. The message may also contain a previous IP address that it has leased from a DHCP server. The client "broadcasts" the message on the network and continues to send the message until it receives a response from the server.
Step 2 Any DHCP server can receive the message and prepare to lease the client an IP address. If a server has a valid configuration for the client, it prepares an "offer" message, which contains the client MAC address, the IP address that the server is offering to lease, a subnet mask, the IP address of the server, and the time length of the lease. The offered address is marked as "reserved." DHCP servers broadcast offer messages over the network.
Step 3 When the client receives the offer messages and accepts one of the IP addresses, the client broadcasts a message to confirm which DHCP server it has accepted an IP address from.
Step 4 Finally, the DHCP server confirms the whole arrangement with the client.
Q 21. How to configure a client machine to use a specific User Class?
Ans: The command to configure a client machine to use a specific user class is ipconfig /setclassid "
Q 22. What is the BOOTP protocol used for, where might you find it in Windows network infrastructure?
Ans:
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