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SBS 2008 DHCP not handing out new leases

    Question

  • I am having problems with DHCP on a network consisting of a server running SBS 2008, 20 Windows 7 workstations and 5 wireless access points. 

    A user complained that they could not connect to the wireless network. I thought that the problem was that the DHCP server was running out of leases. Therefore, I decreased the lease time from 8 days to 2 days.  The DHCP server provided leases for a couple of days and now has totally stopped handing out leases.  It is renewing leases for workstations that are connected to the network.  However, the DHCP server is not handing out new leases.

    I have performed the following attempting to solve the problem:

    -       Rebooted the server

    -       Restarted DHCP

    -       Restarted DNS

    -       Checked network wiring to make sure that a patch cable did not get changed to an incorrect port on the switch creating a loop (no problems located)

    -       Checked for rogue DHCP servers on the network (none found)

    -       Ran fix my network wizard

    -       Ran connect to the internet wizard

    -       The system event log does not have any event log errors except for a warning that the number if available IP addresses is low.  This error should be solved with the decrease in lease time.

    Here is the result of ipconfig/all on a computer that was turned off for a few days and lost its lease:

    Windows IP Configuration

       Host Name . . . . . . . . . . . . : LABSYS02

       Primary Dns Suffix  . . . . . . . : rfag.local

       Node Type . . . . . . . . . . . . : Hybrid

       IP Routing Enabled. . . . . . . . : No

       WINS Proxy Enabled. . . . . . . . : No

       DNS Suffix Search List. . . . . . : rfag.local

     

    Ethernet adapter Local Area Connection:

     

       Connection-specific DNS Suffix  . :

       Description . . . . . . . . . . . : Realtek PCIe GBE Family Controller

       Physical Address. . . . . . . . . : 78-45-C4-0C-74-CD

       DHCP Enabled. . . . . . . . . . . : Yes

       Autoconfiguration Enabled . . . . : Yes

       Link-local IPv6 Address . . . . . : fe80::81d9:37c3:e735:4a6b%11(Preferred)

       Autoconfiguration IPv4 Address. . : 169.254.74.107(Preferred)

       Subnet Mask . . . . . . . . . . . : 255.255.0.0

       Default Gateway . . . . . . . . . :

       DHCPv6 IAID . . . . . . . . . . . : 242763204

       DHCPv6 Client DUID. . . . . . . . : 00-01-00-01-17-B6-11-33-78-45-C4-0C-74-CD

       DNS Servers . . . . . . . . . . . : fec0:0:0:ffff::1%1

                                           fec0:0:0:ffff::2%1

                                           fec0:0:0:ffff::3%1

       NetBIOS over Tcpip. . . . . . . . : Enabled

     

    Here is the result of ipconfig/all from another computer that has not lost its lease:

    Windows IP Configuration

      Host Name . . . . . . . . . . . . : LABSYS01

       Primary Dns Suffix  . . . . . . . : rfag.local

       Node Type . . . . . . . . . . . . : Hybrid

       IP Routing Enabled. . . . . . . . : No

       WINS Proxy Enabled. . . . . . . . : No

       DNS Suffix Search List. . . . . . : rfag.local

     

    Ethernet adapter Local Area Connection:

     

       Connection-specific DNS Suffix  . : rfag.local

       Description . . . . . . . . . . . : Realtek PCIe GBE Family Controller

       Physical Address. . . . . . . . . : 78-45-C4-0C-70-A9

       DHCP Enabled. . . . . . . . . . . : Yes

       Autoconfiguration Enabled . . . . : Yes

       Link-local IPv6 Address . . . . . : fe80::94bb:e622:86bb:5827%11(Preferred)

       IPv4 Address. . . . . . . . . . . : 192.168.50.121(Preferred)

       Subnet Mask . . . . . . . . . . . : 255.255.255.0

       Lease Obtained. . . . . . . . . . : Saturday, October 05, 2013 11:01:50 AM

       Lease Expires . . . . . . . . . . : Saturday, October 12, 2013 2:29:47 PM

       Default Gateway . . . . . . . . . : 192.168.50.1

       DHCP Server . . . . . . . . . . . : 192.168.50.250

       DHCPv6 IAID . . . . . . . . . . . : 242763204

       DHCPv6 Client DUID. . . . . . . . : 00-01-00-01-17-B6-10-E7-78-45-C4-0C-70-A9

       DNS Servers . . . . . . . . . . . : 192.168.50.250

       NetBIOS over Tcpip. . . . . . . . : Enabled

     

    I ran Wireshark and made a couple of captures at boot-up on these two systems to assist with troubleshooting.  The capture on the system that lost its lease shows only DHCP inform and DHCP discover packets.  The capture from the system with a lease has DHCP discover, DHCP request, DHCP inform and DHCP ACK packets.

    If I configure a static IP on a system that has lost its lease, the workstation can connect to SBS; however it does not get an internet connection.

    Any suggestions would be greatly appreciated as to how to solve this problem.

     


    Ken Schmid

    Saturday, October 05, 2013 11:15 PM

Answers

  • I solved the problem last night.  My security software suite had an update to the firewall that I somehow missed the installation.  I removed the 3rd party software firewall on the server and new leases started making it across the network.  I do have a couple of packet captures that I made.  I have not dug into them much yet.  I expect the problem was that some of the DHCP packets were being blocked.  I checked and the SBS firewall automatically was enabled when I removed the McAfee firewall.  I am planning to contact McAfee today and discuss this issue.

    Not sure why the static IP configure did not work.  When I tried a static IP configuration the next day it worked.

    Thanks,

    Ken Schmid


    Ken Schmid

    Tuesday, October 08, 2013 1:01 PM

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