Use Jetpack.exe to Compact a WINS or DHCP Database

Microsoft Windows NT Server includes a utility, Jetpack.exe, that can be used to compact a Windows Internet Name Service (WINS) or Dynamic Host Configuration Protocol (DHCP) database. Microsoft recommends that you compact the WINS database whenever it approaches 30 MB.

If the WINS/DHCP service is a resource within a Windows 2000 Cluster, refer to the following article:

283251  How to Use the Jetpack Utility on a Clustered WINS/DHCP Databas.

 

The correct syntax for Jetpack.exe is:

JETPACK.EXE

Example commands to compact the WINS database:

CD %SYSTEMROOT%\SYSTEM32\WINS
NET STOP WINS
JETPACK WINS.MDB TMP.MDB
NET START WINS

Example commands to compact the DHCP database:

CD %SYSTEMROOT%\SYSTEM32\DHCP
NET STOP DHCPSERVER
JETPACK DHCP.MDB TMP.MDB
NET START DHCPSERVER

In the examples above, Tmp.mdb is a temporary database that is used by Jetpack.exe. Wins.mdb is the WINS database. Dhcp.mdb is the DHCP database.

Jetpack.exe compacts the WINS or DHCP database by doing the following:

1. Copies database information to a temporary database file called Tmp.mdb.
2. Deletes the original database file, Wins.mdb or Dhcp.mdb.
3. Renames the temporary database files to the original filename.

NOTE: During the compact process, Jetpack.exe creates a temporary file with the name that is specified by the temp database name parameter. The temporary file is removed when the compact process is complete. Make sure you do not have a file already existing in WINS or DHCP folder with the same name as the one specified in the temp database name parameter.

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DHCP Lease Process

The first time that a  client (with DHCP enabled) attempts to join a network, it automatically follows an initialization process to obtain a lease from a DHCP server.

1. The DHCP client requests an IP address by broadcasting a message (known as a DHCPDiscover message) to the local subnet.
2. The client is offered an address when a DHCP server responds with a DHCPOffer message containing an IP address, and associated configuration information, available for lease to the client.
3. The client selects the offered address and replies to the server with a DHCPRequest message. Alternatively, the DHCP client might request the IP address that was previously assigned.
4. The client is assigned the address, and the DHCP server sends an acknowledgment message (DHCPAck) approving the lease. Other DHCP option information, such as default gateway and DNS server addresses, might be included in the message.

After the client receives acknowledgment, it configures its TCP/IP properties using any DHCP option information in the DHCPAck message and completes the initialization of TCP/IP.

If no DHCP server responds to the client request, the client can proceed in one of two ways:

1. If APIPA is enabled, the client self-configures a unique IP address in the range 169.254.0.1 through 169.254.255.254.
2. If APIPA has been disabled, the client network initialization fails. The client continues to re-send DHCPDiscover messages in the background until it receives a valid lease from a DHCP server. The client makes four attempts to obtain a lease, one every five minutes.

Configuring Clients for Stateful or Stateless IPv6 Addressing

By default, IPv6 hosts perform stateless address auto configuration automatically.

•    In the DHCPv6 stateless mode clients use DHCPv6 to obtain only configuration options and not an IPv6 address. Stateless clients configure an IPv6 address through a non–DHCPv6-based mechanism, such as by exchanging Router Solicitation and Router Advertisement messages with neighboring routers.

•    In the DHCPv6 stateful mode, clients acquire both the IPv6 address as well as other network configuration parameters through DHCPv6.