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--- networking:dhcp [2020/05/24 08:56] – created bstafford
+++ networking:dhcp [2025/09/19 20:35] (current) – bstafford
@@ Line 1: / Line 1: @@
 ======DHCP======
+Also, remember the port flow:
+  * client to relay source udp-68 to udp-67
+  * relay to server udp-67 to udp-67 (initial request and T2 request)
+  * server to relay udp-67 to udp-67
+  * relay to client udp-67 to udp-68
+  * client direct to server udp-68 to udp-67 (T1 request. Blocked by Azure)
+=====DHCP Relay =====
+[[https://www.netmanias.com/en/post/techdocs/6000/dhcp-network-protocol/understanding-dhcp-relay-agents|Guide]]
+[[https://techcommunity.microsoft.com/blog/azurenetworkingblog/custom-dhcp-support-in-azure/4089674|Microsoft Guide]]
+=====DHCP Option Codes=====
+[[https://www.incognito.com/tutorials/dhcp-options-in-plain-english/|In plain English]].
 ^ DHCP Option ^ Description ^
 |015| Specifies the connection-specific DNS domain suffix to be used by the DHCP client.|
 | 119| DNS Domain Search List option to specify the domain search list used when resolving hostnames with DNS.|
+=====Move Windows DHCP Server=====
+Assuming you are moving DHCP from DC1 to DC2
+On DC1
+  * Open terminal
+  * ''netsh''
+  * ''DHCP''
+  * ''server \\dc1''
+  * ''export c:\w2k3DHCPdb all''
+  * Copy to dc2
+On DC2 (Assuming it is Server 2012)
+  * From within Server Manager, select Add roles and features
+  * Select Role-based of featured-based installation and select Next.
+  * On the Server Selection window, leave the default and select Next. When the Server Roles window opens, select DHCP. Select Add Features in the pop-up window, then select Next.
+  * Once the DHCP install has been completed, select DHCP located in the Server Manager dashboard
+  * Right click the designated DHCP server in the services pane, then select Stop.
+  * Delete the DHCP.mdb file under the folder''C:\windows\system32\DHCP''.
+  * Return to DHCP located in the Server Manager dashboard
+  * Right click the designated DHCP server in the services pane, then select Start.
+  * Right-click on the bottom left hand side of the desktop screen to invoke the admin menu
+  * Select Command Prompt (Admin) to open the cmd prompt using elevated privileges.
+  * ''netsh''
+  * ''DHCP''
+  * ''server \\Name or IP Address''
+  * ''import C:\w2k3DHCPdb''
+  * Close the command prompt when completed.
+Simply setup your scope options for your new Windows Server 2012 DHCP server and then Authorize it within your domain and the  migration is complete. (The GUI should give you a prompt on what to do)
+===== DHCP HA =====
+Split scope (in IPv4) is not efficient. When one server is down, capacity is reduced by half and clients cannot renew with the remaining server. It forces clients using the failed server to go to DHCPDISCOVER and that may cause disruption to the clients as they will change IP address.
+In IPv6, split scope works well because you have such huge IP address scopes.