Ifconfig Renew Dhcp Address Assignments

Let me explains this is small steps:

A completely clean setup.

  • Your PC sends a DHCP requests. (Basically: "Hi. I am $MACaddress here and I would like an IP address for this network")
  • The DHCP server responds with "Hi $MACaddress. Please use these values. They are valid for X hours"

The PC now knowns which IP to use and how long these are valid.

After half X hours (e.g. if the DHCP lease was for 4 hours then this would trigger after 2 hours):

  • PC: "Hi DHCP server, I have this information from you and I want permission to keep using it for a bit longer then I currently have rights. Can I do so?"
  • DHCP server: Sure, keep using them for up to X more hours.
    So valid from a total of 6 hours after the first request: 2+4

This renew actions will not typically change your IP address. You just get permission to use that information for a longer period of time.

Helpful DHCP servers.

A DHCP server usually has a small pool of addresses to hand out. Many will remember which IP address was handed out to which MAC. After that lease expires (or if you release it, e.g. with then the DHCP server is allowed to remember this. When the next request comes it may hand out the first free IP in its pool, or it can hand out the 'fresh' IPs which are not yet used or whose usage is the longer ago. This means that you typically get the same IP even after the lease has expired.

answered May 23 '15 at 11:18

ipconfig

  • 4 minutes to read
  • Contributors

Applies To: Windows Server (Semi-Annual Channel), Windows Server 2016, Windows Server 2012 R2, Windows Server 2012

Displays all current TCP/IP network configuration values and refreshes Dynamic Host Configuration Protocol (DHCP) and Domain Name System (DNS) settings. Used without parameters, ipconfig displays Internet Protocol version 4 (IPv4) and IPv6 addresses, subnet mask, and default gateway for all adapters.

Syntax

Parameters

ParameterDescription
/allDisplays the full TCP/IP configuration for all adapters. Adapters can represent physical interfaces, such as installed network adapters, or logical interfaces, such as dial-up connections.
/allcompartmentsDisplays the full TCP/IP configuration for all compartments.
/displaydnsDisplays the contents of the DNS client resolver cache, which includes both entries preloaded from the local Hosts file and any recently obtained resource records for name queries resolved by the computer. The DNS Client service uses this information to resolve frequently queried names quickly, before querying its configured DNS servers.
/flushdnsFlushes and resets the contents of the DNS client resolver cache. During DNS troubleshooting, you can use this procedure to discard negative cache entries from the cache, as well as any other entries that have been added dynamically.
/registerdnsInitiates manual dynamic registration for the DNS names and IP addresses that are configured at a computer. You can use this parameter to troubleshoot a failed DNS name registration or resolve a dynamic update problem between a client and the DNS server without rebooting the client computer. The DNS settings in the advanced properties of the TCP/IP protocol determine which names are registered in DNS.
/release [<Adapter>]Sends a DHCPRELEASE message to the DHCP server to release the current DHCP configuration and discard the IP address configuration for either all adapters (if an adapter is not specified) or for a specific adapter if the Adapter parameter is included. This parameter disables TCP/IP for adapters configured to obtain an IP address automatically. To specify an adapter name, type the adapter name that appears when you use ipconfig without parameters.
/release6[<Adapter>]Sends a DHCPRELEASE message to the DHCPv6 server to release the current DHCP configuration and discard the IPv6 address configuration for either all adapters (if an adapter is not specified) or for a specific adapter if the Adapter parameter is included. This parameter disables TCP/IP for adapters configured to obtain an IP address automatically. To specify an adapter name, type the adapter name that appears when you use ipconfig without parameters.
/renew [<Adapter>]Renews DHCP configuration for all adapters (if an adapter is not specified) or for a specific adapter if the Adapter parameter is included. This parameter is available only on computers with adapters that are configured to obtain an IP address automatically. To specify an adapter name, type the adapter name that appears when you use ipconfig without parameters.
/renew6 [<Adapter>]Renews DHCPv6 configuration for all adapters (if an adapter is not specified) or for a specific adapter if the Adapter parameter is included. This parameter is available only on computers with adapters that are configured to obtain an IPv6 address automatically. To specify an adapter name, type the adapter name that appears when you use ipconfig without parameters.
/setclassid <Adapter>[ Configures the DHCP class ID for a specified adapter. To set the DHCP class ID for all adapters, use the asterisk (*) wildcard character in place of Adapter. This parameter is available only on computers with adapters that are configured to obtain an IP address automatically. If a DHCP class ID is not specified, the current class ID is removed.
/showclassid <Adapter>Displays the DHCP class ID for a specified adapter. To see the DHCP class ID for all adapters, use the asterisk (*) wildcard character in place of Adapter. This parameter is available only on computers with adapters that are configured to obtain an IP address automatically.
/?Displays Help at the command prompt.
  • This command is most useful on computers that are configured to obtain an IP address automatically. This enables users to determine which TCP/IP configuration values have been configured by DHCP, Automatic Private IP Addressing (APIPA), or an alternate configuration.
  • If the name you supply for Adapter contains any spaces, use quotation marks around the adapter name (example: "Adapter Name").
  • For adapter names, ipconfig supports the use of the asterisk (*) wildcard character to specify either adapters with names that begin with a specified string or adapters with names that contain a specified string. For example, Local\* matches all adapters that start with the string Local and *Con\* matches all adapters that contain the string Con.

Examples

To display the basic TCP/IP configuration for all adapters, type:

To display the full TCP/IP configuration for all adapters, type:

To renew a DHCP-assigned IP address configuration for only the Local Area Connection adapter, type:

To flush the DNS resolver cache when troubleshooting DNS name resolution problems, type:

To display the DHCP class ID for all adapters with names that start with Local, type:

To set the DHCP class ID for the Local Area Connection adapter to TEST, type:

Additional references

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