Network nodes require an IP address configuration that usually comprises the IP address, subnet mask, default gateway IP for the router, name servers and other values. Show
Administrators can manually set this information, resulting in a static configuration. A Dynamic Host Configuration Protocol (DHCP) server can also dynamically provide the information. Generally, servers, routers, network printers and other such devices have a static configuration. Workstations, laptops, phones, tablets and other end-user devices receive their configuration via DHCP. Client devices lease their IP address configuration by using the following four-step DORA process:
The lease must be renewed by the client periodically. Now that we've briefly reviewed how IP addresses are allocated and the lease generation process, let's delve into more detail about how to configure the Windows Server DHCP service. 1. Install DHCP on Windows Server 2019The DHCP service is not automatically installed on Windows Server 2019. It is easy to add, however, using either Server Manager or Windows PowerShell. To add DHCP using Server Manager, select Add Roles and Features, and then select DHCP in the Roles list. To add the DHCP role using the command line, open Windows PowerShell (Admin), and type the following: Install-WindowsFeature DHCP -IncludeManagementTools
The installation takes about one minute to complete. Once admins install the DHCP service, they can manage it by selecting Tools > DHCP. 2. Authorize DHCP in Active DirectoryWindows-based DHCP servers must be registered with Active Directory (AD) before they begin offering IP address configurations to clients. Right-click on the server node in the DHCP console, and select Authorize to accomplish this authorization. You need Enterprise Admin privileges to authorize DHCP. 3. Create a scopeBefore building the first pool of available IP addresses, it's critical to plan the deployment. Devices, such as servers, routers and even printers, may have static IP address configuration. Make sure you have identified these addresses and that you allow for them in scope. Many administrators place all statically assigned IP addresses at the front of the scope. Here is a simple example design:
You also need to gather additional configuration details, including the following:
4. Configure and activate the scopeOnce you have documented the above values, you can configure the scope. Right-click the server node in the DHCP console, and then select New Scope. A wizard prompts you for the information you collected above. These settings can be changed later. Once activated, the DHCP server begins responding to DHCP client discover messages by offering IP addresses. The scope can be deactivated, the DHCP service can be stopped or restarted, and the DHCP server can be deauthorized in AD. 5. DNS registrationDNS relates easy-to-remember hostnames with difficult-to-remember IP addresses. This database can be populated in several ways. One method is to configure the DHCP server to create resource records for the client. The DHCP server can be set to create A records (hostname to IP address), pointer (PTR) records (IP to hostname) or both. The default is for DHCP to create the PTR record, while the client itself registers its record with DNS. Administrative DHCP tasksThe DHCP service is simple to configure. But sys admins often find some additional settings to be useful. Create reservationIn some cases, it's useful to allow a client machine to maintain a consistent IP address. While you could set the IP address configuration statically, it's often better to reserve the IP address for the client in DHCP. The client goes through the DORA process to receive its settings, so values, such as router and name resolution servers, can still be updated via DHCP. DHCP failoverWith Windows Server 2012, Microsoft introduced DHCP failover. It seems many administrators are unaware of this capability. Configuration is straightforward and requires no special software. To configure DHCP failover, use the following steps:
LogsManaging service log files is a standard function for sys admins. DHCP writes messages to Event Viewer and to text files. Sys admins can check the system log for general DHCP and network messages. They can find DHCP entries by drilling down to Applications and Services > Microsoft > Windows > DHCP-Server > Microsoft-Windows-DHCP-Server-Events > Operational. DHCP also generates text-based log files stored at C:\Windows\System32\dhcp. These logs are extremely useful for troubleshooting. They can display information for why the server was unable to lease configurations to clients. Note that the text file logs are named based on days of the week and are overwritten weekly. If you want to retain these logs, you must rename them before the upcoming day of the week can overwrite them.
Be careful of conflicting scopesAs more subnets -- and, therefore, more DHCP scopes -- are added to the network, it's imperative that sys admins accurately document the IP address ranges. Overlapping scopes, where two DHCP servers are offering the same IP addresses to clients, result in a variety of network communications issues. This is part of the reason why Microsoft requires DHCP servers to be authorized in AD. That authorization can only be implemented by Enterprise Admins, who should have enough broad knowledge of network configuration to prevent conflicting scopes. Avoid duplicate IP address offersOne of the most serious misconfigurations is a client computer configured with a static IP address that falls within the DHCP server's scope. In that case, the server can offer the IP address to a client because it is unaware of the static IP. This results in an IP address conflict. The Windows DHCP service can be configured to ping an IP address before offering it to a client. If the ping returns a response, the DHCP server knows the address is already in use and should not be offered. The server offers a different address to the client. The ping request occurs between the Discover and Offer steps of the lease generation process. It introduces a significant delay, so only configure this setting if you have a real concern about undocumented static IP addresses on client devices. ConclusionMicrosoft has made the configuration of a DHCP server straightforward. Make sure you have a solid understanding of the entire network's IP address configurations before you begin and plan your scope around both dynamic and static IP address assignments. The DHCP role is not installed by default, so the first step is to add it. From there, create a new scope based on your plan. Add any options, such as DNS and reserved addresses. Review log files regularly. DHCP is simple but critical for network communication. What is enable DHCP relay?A DHCP relay agent is a host or router that forwards DHCP packets between clients and servers. Network administrators can use the DHCP Relay service of the SD-WAN appliances to relay requests and replies between local DHCP Clients and a remote DHCP Server.
Which of the following roles must be installed in order to deploy a DHCP relay agent on Windows Server 2016?You need to install the Remote Access service feature to use Windows Server 2016 as a DHCP relay agent. 2.
What function does a DHCP relay agent perform?The DHCP relay agent operates as the interface between DHCP clients and the server. The DHCP Relay Agent relays DHCP messages between DHCP clients and DHCP servers on different IP networks.
Which of the following network components are capable of functioning as DHCP relay agents?Which of the following network components are typically capable of functioning as DHCP relay agents? B. Most IP routers have DHCP relay agent capabilities built into them. If the routers connecting your subnets are so equipped, you can use them as relay agents, eliminating the need for a DHCP server on each subnet.
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