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6 Appendix A: Product Behavior

  • Article

The information in this specification is applicable to the following Microsoft products or supplemental software. References to product versions include updates to those products.

  • Windows Server 2012 operating system

  • Windows Server 2012 R2 operating system

  • Windows Server 2016 operating system

  • Windows Server operating system

  • Windows Server 2019 operating system

  • Windows Server 2022 operating system

  • Windows Server 2025 operating system

Exceptions, if any, are noted in this section. If an update version, service pack or Knowledge Base (KB) number appears with a product name, the behavior changed in that update. The new behavior also applies to subsequent updates unless otherwise specified. If a product edition appears with the product version, behavior is different in that product edition.

Unless otherwise specified, any statement of optional behavior in this specification that is prescribed using the terms "SHOULD" or "SHOULD NOT" implies product behavior in accordance with the SHOULD or SHOULD NOT prescription. Unless otherwise specified, the term "MAY" implies that the product does not follow the prescription.

<1> Section 2.1:  The Windows DHCP server listens by default on port 647 but allows any port number to be configured by using the registry key "DhcpFailoverPort" under HKLM\SYSTEM\CurrentControlSet\Services\DhcpServer\Parameters.

<2> Section 2.2:  The Windows DHCP servers use SHA-256 as the default interactive cryptographic hash function but allow any hash function to be configured by using the registry key "DhcpFailoverCryptoAlgorithm" under HKLM\SYSTEM\CurrentControlSet\Services\DhcpServer\Parameters.

<3> Section 3.1.2.1:  The Windows DHCP servers configure the Safe Period timer interval by using the R_DhcpV4FailoverCreateRelationship method ([MS-DHCPM] section 3.2.4.90) and the R_DhcpV4FailoverSetRelationship method ([MS-DHCPM] section 3.2.4.91).

<4> Section 3.1.2.2:  The Windows DHCP servers configure the Connect Retry timer interval by using the registry key "DhcpFailoverConnectionRetryTime" under HKLM\SYSTEM\CurrentControlSet\Services\DhcpServer\Parameters.

<5> Section 3.1.2.3:  The Windows DHCP servers configure the Startup timer interval by using the registry key "DhcpFailoverStartUpTimer" under HKLM\SYSTEM\CurrentControlSet\Services\DhcpServer\Parameters.

<6> Section 3.1.2.4:  The Windows DHCP servers configure the tReceive timer interval by using the registry key "DhcpFailoverReceiveTimer" under HKLM\SYSTEM\CurrentControlSet\Services\DhcpServer\Parameters.

<7> Section 3.1.2.5:  The Windows DHCP servers configure the tSend timer interval to be equal to one-third the interval value for the tReceive timer which is configured by using the registry key "DhcpFailoverReceiveTimer" under HKLM\SYSTEM\CurrentControlSet\Services\DhcpServer\Parameters.

<8> Section 3.1.2.6:  The Windows DHCP servers do not implement this timer.

<9> Section 3.1.5:  The Windows DHCP server allows a time difference of one minute by default but supports configuration of the interval by using the registry key "DhcpMsgSyncDeltaTime" under HKLM\SYSTEM\CurrentControlSet\Services\DhcpServer\Parameters.

<10> Section 3.1.6.6:  The Windows DHCP servers do not implement this timer.

<11> Section 3.2.2.1:  The Windows DHCP servers configure the Address Rebalancing timer interval by using the registry key "DhcpFailoverAddrRebalacingTimeInt" under HKLM\SYSTEM\CurrentControlSet\Services\DhcpServer\Parameters.

<12> Section 3.3.3:  The Windows DHCP server listens by default on port 647 but allows any port number to be configured by using the registry key "DhcpFailoverPort" under HKLM\SYSTEM\CurrentControlSet\Services\DhcpServer\Parameters.

<13> Section 5.1: The Windows DHCP servers use SHA-256 as the default interactive cryptographic hash function but allow any hash function to be configured by using the registry key "DhcpFailoverCryptoAlgorithm" under HKLM\SYSTEM\CurrentControlSet\Services\DhcpServer\Parameters.