"DHCP Server", DHCP Scope, Reservation, Failover, Split Scope

"DHCP Server", Step by step on DHCP Scope, Super Scope, DHCP Reservation, DHCP Failover, and Split Scope.

Assignment Submitted to Prof. Leng Phearun, Network Operating System

I- DHCP

The Dynamic Host Configuration Protocol (DHCP) service automatically configures the Internet Protocol (IP) address and other TCP/IP settings on network computers by assigning addresses from a pool (called a scope) and reclaiming them when they are no longer in use.


Adding DHCP Role
Log on to Windows Server 2012 R2 using an account with Administrative privileges.
1) In the Server Manager window, click Manage and then click Add Roles and Features.
2) The Add Roles and Features Wizard appears, displaying the Before you begin page.
3) Click Next. The Select Installation Type page appears.
4) Leave the Role-based or feature-based installation radio button selected and click Next. The Select Destination Server page appears.
5) Select the server on which you want to install the roles and/or features and click Next. The Select Server Roles page appears.
6) Select the DHCP Server check box. An Add features that are required for DHCP Server dialog box appears.
7) Click Add Features, and then click Next. The Select features page appears.
8) Click Next. The DHCP Server page appears.
9) Click Next. The Confirm installation selections page appears.
10) Click Install. The Installation progress page appears as the wizard installs the role.
11) Click Close. The wizard closes.

II- IPv4 Address

The IPv4 address space consists of 32-bit addresses, notated as four 8-bit decimal values from 0 to 255, separated by periods, as in the example 192.168.43.100. This is known as dotted decimal notation, and the individual 8-bit decimal values are called octets or bytes. Each address consists of network bits, which identify a network, and host bits, which identify a particular device on that network. To differentiate the network bits from the host bits, each address must have a subnet mask.

A subnet mask is another 32-bit value consisting of binary 1 bits and 0 bits. When compared to an IP address, the bits corresponding to the 1’s in the mask are the network bits, whereas the bits corresponding to the 0’s are the host bits. Thus, if the 192.168.43.100 address mentioned earlier has a subnet mask of 255.255.255.0 (which in binary form is 11111111.11111111.11111111.00000000), the first three octets (192.168.43) identify the network and the last octet (100) identifies the host.

The original Internet Protocol (IP) standard defines three classes of IP addresses, which provide support for networks of different sizes.

III- DHCP Scope

DHCP scopes is a range of IP addresses that can be allocated to clients.

Creating a Scope

Log on to Windows Server 2012 R2, using an account with Administrative privileges.

1) In the Server Manager window, click Tools and then click DHCP. The DHCP console appears.

2) Expand the server and IPv4 nodes.

3) Right-click the IPv4 node and, from the context menu, select New Scope. The New Scope Wizard appears, displaying the Welcome page.

4) Click Next. The Scope Name page appears.

5) Type a name for the scope into the Name text box and click Next. The IP Address Range page appears.

6) In the Start IP address text box, type the first in the range of addresses you want to assign. In the End IP address text box, type the last address in the range.

7) In the Subnet Mask text box, type the mask value for the subnet on which the scope will operate and click Next. The Add Exclusions and Delay page appears.

8) In the Start IP address and End IP address text boxes, specify a range of addresses you want to exclude from the scope. You can also specify a delay interval between the server’s receipt of DHCPDISCOVER messages and its transmission of DHCPOFFER messages. Then click Next. The Lease Duration page appears.

9) Specify the length of the leases for the addresses in the scope and click Next. The Configure DHCP Options page appears.

10) Select Yes, I want to configure these options now and click Next. The Router (Default Gateway) page appears.

11) In the IP address text box, specify the address of a router on the subnet served by the scope and click Add. Then click Next. The Domain Name and DNS Servers page appears.

12) In the Server name text box, type the name of a DNS server on the network and click Resolve, or type the address of a DNS server in the IP address text box and click Add. Then click Next. The WINS Servers page appears.

13) Click Next. The Activate Scope page appears.

14) Select Yes, I want to activate this scope now and click Next. The Completing the New Scope Wizard page appears.

15) Click Finish. The wizard closes.

A- Super Scope

A superscope is the grouping of multiple scopes into a single administrative entity. By using superscopes, you can support larger subnets.

A superscope can be used if a scope runs out of addresses and you cannot add more addresses from the subnet. Instead, you can add a new subnet to the DHCP server. You then perform multinetting, where you lease addresses to clients in the same physical network, but the clients will be in a separate network logically by subnet.

Configuring Superscope

To configure a superscope out of two scopes, perform the following steps:

1) Right-click IPv4, and click New Superscope.

2) When the New SuperScope Wizard begins, type Superscope name (For example: Super1) in the Name text box, and click Next.

3) On the Select Scopes page, press the Control key and hold it down. Then click Scope1 and Scope2. Release the Control key. Click Next.

4) Click Finish. The superscope shows in the DHCP console.

B- DHCP Reservation

A DHCP reservation is a specific IP address, within a scope that is permanently reserved for lease use to a specific DHCP client.

Because the DHCP dynamic allocation method allows for the possibility that a computer’s IP address could change, it is not appropriate for these particular roles. However, it is still possible to assign addresses to these computers with DHCP by using manual, instead of dynamic, allocation.

Configuring DHCP Reservation

We need to know MAC address of the client we are going to configure. To know it:

1) Run Command

2) Type ipconfig/all

3) You will see MAC address in Physical Address

Reservation

1) In the DHCP snap-in, expand the scope for which you want to create a reservation.

2) Select and right-click Reservations, and then click New Reservation.

3) In the New Reservation dialog box, enter the Reservation name, IP address, MAC address, and Description of the reservation.

4) Select the appropriate Supported types: DHCP only, BOOTP only, or Both.

5) Click Add.

Active IP Address to Client

1) In the DHCP snap-in, expand the scope

2) Select Address Pool

3) Right click on address, then click Active

IV- Configuring High Ability of DHCP

DHCP is an essential service that allows most clients and some servers to communicate on the network. As clients are turned on, or when a client renews a lease, the DHCP server must be available to assign or renew the lease. So, you need to take steps to ensure that DHCP services are available.

In Windows Server 2012 R2, there are two common high availability options available for DHCP Server deployment (has another few way, but these two are commonly used), DHCP Failover and Slip Scope. These two configuring require two DHCP in which:

+ DHCP1 is a computer running Windows Server 2012, providing the following services:

- A domain controller for the contoso.com Active Directory domain.

- An authoritative DNS server for the contoso.com DNS zone.

- A DHCP server. 

+ DHCP2 is a computer running Windows Server® 2012, providing the following services:

- A DHCP server.

Configuring DHCP1 and DHCP2

+ DHCP1

- Configure TCP/IP

1) Click Start, type ncpa.cpl, and then press ENTER. The Network Connections control panel will open.

2) In Network Connections, right-click Wired Ethernet Connection and then click Properties.

3) Double-click Internet Protocol Version 4 (TCP/IPv4).

4) On the General tab, choose Use the following IP address.

5) Next to IP address type IP (For example: 10.0.0.1) and next to Subnet mask type 255.255.255.0. It is not necessary to provide an entry next to Default gateway.

6) Next to Preferred DNS server, type the same IP as the above IP address (10.0.0.1.)

7) Click OK twice, and then close the Network Connections control panel.

- Install AD DS, DNS Server, and DHCP Server (Follow what you have learned)

- Create a domain administrator account

1) On the Server Manager menu bar, click Tools, and then click Active Directory Users and Computers.

2) In the Active Directory Users and Computers console tree, double-click contoso.com, right-click Users, point to New, and then click User.

3) In the New Object – User dialog box, type name of user (For example: user1) under User logon name and next to Full name, then click Next.

4) Next to Password and Confirm password, type a password (for the user1 account).

5) Clear the checkbox next to User must change password at next logon, select the Password never expires checkbox, click Next, and then click Finish.

6) Double-click on user (user1) and then click the Member Of tab.

7) Click Add, type domain admins under Enter the object names to select, click OK twice, and then close the Active Directory Users and Computers console.

8) Click Start, click Administrator, and then click Sign out.

9) Sign in to the computer using the user1 credentials by clicking the left arrow next to YOUR DOMAIN\Administrator and then clicking Other user.

+ DHCP2

- Configure TCP/IP

1) Click Start, type ncpa.cpl, and then press ENTER. The Network Connections control panel will open.

2) In Network Connections, right-click Wired Ethernet Connection and then click Properties.

3) Double-click Internet Protocol Version 4 (TCP/IPv4).

4) On the General tab, choose Use the following IP address.

5) Next to IP address type IP the same as DHCP1 and next to Subnet mask type 255.255.255.0. It is not necessary to provide an entry next to Default gateway.

6) Next to Preferred DNS server, type the same as DHCP1

7) Click OK twice, and then close the Network Connections control panel.

- Install DHCP

1) In the Server Manager navigation pane, click Local Server and then click the name next to Computer name. The System Properties control panel will open.

2) Under Member of, select Domain (Domain of DHCP1), and then click OK.

3) When you are prompted to provide credentials to join the domain, enter the credentials for the user1 account that was created previously and then click OK.

4) Confirm that computer name and domain changes were successful, click OK twice, and then click Close.

5) When you are prompted to restart the computer, click Restart Now.

6) After restarting the computer, sign-in using the YOUR DOMAIM\user1 account.

7) Add DHCP Role (Follow what you have learned, and IP address scope range is the same as DHCP1)

A- DHCP Failover

DHCP failover in Windows Server 2012 enables administrators to deploy a highly resilient DHCP service to support a large enterprise without the challenges of the options. The main goals of the feature are the following:

1) Provide DHCP service availability at all times on the enterprise network.

2) If a DHCP server is no longer reachable, the DHCP client is able to extend the lease on its current IP address by contacting another DHCP server on the enterprise network.

The DHCP server failover feature provides the ability to have two DHCP servers provide IP addresses and option configuration to the same subnet or scope, providing for continuous availability of DHCP service to clients. The two DHCP servers replicate lease information between them, allowing one server to assume responsibility for servicing of clients for the entire subnet when the other server is unavailable. It is also possible to configure failover in a load-balancing configuration with client requests distributed between the two servers in a failover relationship.

Configuring DHCP Failover

First, configure a failover relationship using DHCP1 and DHCP2.

To configure a failover relationship

1) On DHCP2, open the DHCP console, right-click DHCP scope and then click Configure failover.

2) In the Configure Failover wizard, click Next.

3) In Specify the partner server to use for failover, next to Partner Server, type name of DHCP2 (For example: dhcp1.contoso.com) and then click Next.

4) In Create a new failover relationship, type a name next to Relationship Name, or accept the default name that is displayed (dhcp2.contoso.com-dhcp1.contoso.com).

5) Type a shared secret for this failover relationship next to Shared Secret (ex: secret).

6) Change the value next to Maximum Client Lead Time to 0 hours and 1 minute.

7) Review the options available in the drop-down menu next to Mode. You can choose Load balance or Hot standby. By default, Load balance mode is chosen.

8) Click Next and then click Finish.

9) Verify that failover configuration was successful, and then click Close.

10) On DHCP1, refresh the DHCP console and verify that the same DHCP scope configuration that is present on DHCP2 is now present on DHCP1.

To edit properties of the failover relationship and demonstrate hot standby mode

1) On DHCP1 or DHCP2, in the DHCP console, right-click the Contoso-scope1 DHCP scope and then click Properties.

2) Click the Failover tab.

3) Click Edit and then choose Hot Standby Mode.

4) Depending on which DHCP server you are configuring, the local server will be assigned either Active or Standby status. The status is displayed next to Role of this server.

B- Split Scope

Use two DHCP servers to assign IP addresses. Eighty percent of the available addresses are assigned on the primary server, and 20 percent of the available addresses are assigned to a secondary server. When the primary server is down, the secondary server can assign IP addresses long enough for you to fix or replace the primary server.

Configuring Split Scope

1) Open Server Manager, open the Tools menu, and click DHCP. The DHCP console opens.

2) Right-click a scope that you created on the DHCP server, click Advanced, and click

3) Split-Scope.

4) When the DHCP Split-Scope Configuration Wizard starts, click Next.

5) On the Additional DHCP Server page, type the name of the secondary DCHP server,

6) and click Next.

7) On the Percentage of Split page, the slider bar is already set at 80. Click Next.

8) On the Delay in DHCP Offer page, the host DHCP server and the added DHCP server

9) have a delay of 0 milliseconds. Change the delay of the added DHCP server to 500.

10) Click Next.

11) When the wizard is complete, click Finish.

12) On the Summary of Split-Scope page, click Close.