DHCP module

The DHCP module tracks requests and answers for dynamic IP assignments in networks. This allows to resolve self-announced system names to actual IP addresses. Also, the module gives an overview about running DHCP servers in the network, allowing to identify problems with IP number assignments.

Web interface

DHCP module.png


The overview tab shows all IPs that have been assigned dynamically by any DHCP server seen on the network. The columns are as follows:

  • IP address: This is the IP address assigned to the client computer. Clicking on the address link will lead to the corresponding page of the IP module.
  • Alternative names: Shows all known names from different sources for the IP address.
  • Self-announced host name: During the DHCP request, the client may tell its own host name. This columns shows this value. Depending on the network configuration, this name might be used for DNS name look as well.
  • MAC address: This is the address of the network device from the client computer. Clicking on the address link will lead to the corresponding page of the MAC module. The vendor name who owns the MAC address is also shown as well as custom defined names.
  • Subnet mask: This is the netmask corresponding to the assigned IP address.
  • DHCP server IP: This is the IP address of the server which assigned the dynamic IP address to the client.
  • Router IP: The DHCP server will tell the client in most cases an IP of the router so that the client can set up a routing table entry for the network.
  • DNS IP: In many cases the DHCP server will also tell the client an IP address of a name server within the network.
  • Issue time: This columns displays the time when the IP address has been assigned to the client.
  • Lease time: This is the time span for which the IP address assignment is valid.
  • Validity: This columns prints in green color for how long the IP address is still valid, or in red color for how long the IP address is expired.

The search bar allows to filter for a specific IP or name, the clear button clears the filter to show all entries again.

DHCP server

The DHCP server tab presents a special view of the DHCP information. This view gives a quick overview of all DHCP servers that have been seen on the network. It shows the alternative name of the IP, if available. The table also contains the time of the last issued IP address by this server, and the number of distinct IP addresses that have been assigned. You can click on the number to see all IP addresses assigned by this server. Having multiple DHCP server is often a problem within network configurations which lead to network problems due to wrong IP address assignments. IP statistics

Resetting statistics

The stored data about each IP can be removed by clicking on the trashcan button on the top right of the DHCP statistics web page.