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Dynamic Host configuration Protocol (DHCP) is a client / server protocol that automatically provides Internet Protocol (IP) hosts with their IP addresses and other relevant configuration information, such as subnet masks and default gateways. RFC 2131 and 2132 define DHCP as the Internet Engineering Task Force (IETF) standard based on Boot Protocol (BOOTP), which shares many implementation details with DHCP. DHCP allows hosts to obtain the required TCP / IP configuration information from the DHCP server.

Windows Server 2016 includes a DHCP server, an optional network server role that you can deploy on the network to lease IP addresses and other information from DHCP clients. All Windows-based client operating systems include the DHCP client as part of TCP / IP, and the DHCP client is enabled by default.

DHCP function:

Each device on a TCP / IP-based network must have a unique unicast IP address to access the network and its resources. If you do not have DHCP, you must manually configure the IP address of a new computer or computer that is moved from one subnet to another, and you must manually recycle the IP address of a computer that is removed from the network.

With DHCP, the whole process can be automated and centrally managed. The DHCP server maintains a pool of IP addresses and leases an address when it starts any DHCP-enabled client on the network. Because IP addresses are dynamic (leased) rather than static (permanently assigned), addresses that are no longer in use are automatically returned to the pool for reassignment.

The network administrator sets up a DHCP server, maintains TCP / IP configuration information, and provides address configuration for DHCP-enabled clients in the form provided by leases. The DHCP server stores configuration information in a database that contains the following:

Valid TCP / IP configuration parameters for all clients on the network.

A valid IP address maintained in the pool that is assigned to clients and excluded addresses.

Reserved IP address associated with a specific DHCP client. This allows a single IP address to be assigned consistently to a single DHCP client.

The duration of the lease, or the length of time that the IP address can be used if the lease is renewed.

DHCP-enabled clients receive when accepting a lease:

The valid IP address of the subnet to which it is connected.

The requested DHCP option, which is an additional parameter that the DHCP server is configured to assign to the client. Some examples of DHCP options are routers (default gateways), DNS servers, and DNS domain names.

Advantages of DHCP:

Reliable IP address configuration. DHCP minimizes configuration errors caused by manual IP address configuration, such as typographical errors, or address conflicts caused by simultaneous allocation of IP addresses to multiple computers.

Reduce network management. DHCP includes the following features to reduce network management:

Centralized and automated TCP / IP configuration.

TCP / IP configuration can be defined from a central location.

You can assign a full range of additional TCP / IP configuration values through the DHCP option.

Effectively handle IP address changes for clients that must be updated frequently, such as IP address changes for portable devices that move to different locations on the wireless network.

Use the DHCP relay agent to forward the initial DHCP message, eliminating the need to use a DHCP server on each subnet.

After introducing the conceptual content, we begin to introduce the dynamic Host configuration Protocol (DHCP) features that are new or changed in Windows Server 2016.

DHCP is an Internet Engineering Task Force (IETF) standard designed to reduce the administrative burden and complexity of configuring hosts on TCP / IP-based networks such as private Intranet. By using the DHCP server service, the process of configuring TCP / IP on the DHCP client is automatic.

The following sections provide information about the new features and functional changes of DHCP.

DHCP Subnet selection option

DHCP now supports options 118 and 82 (sub-option 5). You can use these options to allow DHCP proxy clients and relay agents to request IP addresses for specific subnets and for specific IP address ranges and ranges.

If you are using a DHCP relay agent configured with DHCP option 82 (suboption 5), the relay agent can request the IP address lease of the DHCP client from a specific IP address range.

Newly recorded event of failed DNS registration for DHCP server

DHCP now includes logging events on the DNS server where the DHCP server DNS records failed registration.

Add: the following new DHCP events can help you easily identify when DNS registration failed due to misconfiguration or loss of the DNS reverse lookup zone.

The forwarding record registration for ID event value 20317DHCPv4.ForwardRecordDNSFailureIPv4 address 1 and FQDN%2 failed with error 3. This may be because the forward lookup zone for this record does not exist on the DNS server. Forwarding record registration for 20318DHCPv4.ForwardRecordDNSTimeoutIPv4 address 1 and FQDN%2 failed with error 3. Registration of PTR records for 20319DHCPv4.PTRRecordDNSFailureIPv4 address 1 and FQDN%2 failed with error 3. This may be because the reverse lookup zone for this record does not exist on the DNS server. Registration of PTR records for 20320DHCPv4.PTRRecordDNSTimeoutIPv4 address 1 and FQDN%2 failed with error 3. Forwarding record registration for 20321DHCPv6.ForwardRecordDNSFailureIPv6 address 1 and FQDN%2 failed with error 3. This may be because the forward lookup zone for this record does not exist on the DNS server. Forwarding record registration for 20322DHCPv6.ForwardRecordDNSTimeoutIPv6 address 1 and FQDN%2 failed with error 3. Registration of PTR records for 20323DHCPv6.PTRRecordDNSFailureIPv6 address 1 and FQDN%2 failed with error 3. This may be because the reverse lookup zone for this record does not exist on the DNS server. Registration of PTR records for 20324DHCPv6.PTRRecordDNSTimeoutIPv6 address 1 and FQDN%2 failed with error 3. PTR record registration for 20325DHCPv4.ForwardRecordDNSErrorIPv4 address 1 and FQDN%2 failed with error 3 (4). Forwarding record registration for 20326DHCPv6.ForwardRecordDNSErrorIPv6 address 1 and FQDN%2 failed, error 3 (4) 20327DHCPv6.PTRRecordDNSErrorIPv6 address 1 and PTR record registration for FQDN%2 failed, error 3 (4).

DHCP NAP is not supported in Windows Server 2016

Network access Protection (NAP) is not recommended in Windows Server 2012 R2, and in Windows Server 2016, the DHCP server role no longer supports NAP.

NAP support introduced the DHCP server role in Windows Server 2008 and is supported in Windows client and server operating systems prior to Windows 10 and Windows Server 2016. The following table summarizes the support for NAP in Windows Server.

Operating system

NAP support

Windows Server 2008

Support

Windows Server 2008 R2

Support

Windows Server 2012

Support

Windows Server 2012 R2

Support

Windows Server 2016

Not supported

In a NAP deployment, a DHCP server running an operating system that supports NAP can act as a NAP enforcement point for NAP DHCP enforcement methods.

In Windows Server 2016, the DHCP server does not enforce the NAP policy, and the DHCP scope cannot enable NAP. DHCP client computers that are also NAP clients use DHCP requests to send health statements (SoH). If the DHCP server is running Windows Server 2016, these requests are processed as if SoH did not exist. The DHCP server grants a normal DHCP lease to the client.

If the server running Windows Server 2016 is a RADIUS agent that forwards agent forwarding requests to the Network Policy Server (NPS) that supports NAP, these NAP clients are evaluated by NPS as not supporting NAP and NAP processing fails.

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