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06-02-2011, 11:44   #1
_Kaiser_
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Server 2008 R2: DHCP Lease times?

Hey all,

So I've a test box running with Server 2008 R2 that is also setup as a DC, DNS, and DHCP server

The problem is wireless devices like say my Android phone.. initially it connects fine and gets an IP and works away, but the next day it'll be unable to get an address and I either have to manually delete the lease on the server or give it a manual IP (in both cases it then works fine again)

I've experimented with different lease times from the default 8 days, to longer, and shorter but still having issues. There's also wired clients to consider of course and these seem ok anyway.

Just wondering what others set the lease time to as I'm sure with wireless-enabled devices like Blackberrys and laptops etc being used it's probably a common problem.

Any feedback appreciated
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06-02-2011, 13:48   #2
Static M.e.
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I'm not sure I get the problem.

How are you connecting the Wireless devices to the Server?

Quote:
I've experimented with different lease times from the default 8 days, to longer, and shorter but still having issues. There's also wired clients to consider of course and these seem ok anyway.
-- I don't think the problem is the DHCP lease times etc.. Its most likely the intermediary device or the phone settings
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06-02-2011, 13:51   #3
kippy
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Quote:
Originally Posted by Static M.e. View Post
I'm not sure I get the problem.

How are you connecting the Wireless devices to the Server?



-- I don't think the problem is the DHCP lease times etc.. Its most likely the intermediary device or the phone settings
Yep, highly unlikely the issue is with the server or the servers DHCP lease times.
How you are connecting to the "network" and the devices between the android device and the server are fairly important.
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06-02-2011, 14:26   #4
_Kaiser_
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The wireless clients are connecting to a Buffalo router which is acting as a gateway for the server. DHCP is turned off on this router as the addresses are assigned by the 2008 box.

If it's a "first time" connect from the phone it sees the WLAN, accepts the (WPA2 PSK) key and gets a valid IP address from the server and all is well.
If though I come in the next day it won't get an address... just sits trying to get an IP from the server.

The only way I've found around it so far is to delete the leases on the DHCP server and then it will reconnect, or if I manually define the IP settings on the phone it works fine.

Unless I try getting the router to issue a 2nd set of DHCP addresses? (eg: DHCP server: 20-40, router: 41-50)
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06-02-2011, 19:49   #5
swampgas
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Quote:
Originally Posted by Kaiser2000 View Post
The wireless clients are connecting to a Buffalo router which is acting as a gateway for the server. DHCP is turned off on this router as the addresses are assigned by the 2008 box.

If it's a "first time" connect from the phone it sees the WLAN, accepts the (WPA2 PSK) key and gets a valid IP address from the server and all is well.
If though I come in the next day it won't get an address... just sits trying to get an IP from the server.

The only way I've found around it so far is to delete the leases on the DHCP server and then it will reconnect, or if I manually define the IP settings on the phone it works fine.

Unless I try getting the router to issue a 2nd set of DHCP addresses? (eg: DHCP server: 20-40, router: 41-50)
You said earlier you set the lease time to 8 days, does it take 8 days for the problem to occur?

Maybe it's an issue with the DHCP lease being renewed?

Do you have a laptop on wireless that sees the same problem?

I'm not a windows guy specifically, but I'd be tempted to install wireshark on the DHCP server and have a look at whether the DHCP request is even reaching it.
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07-02-2011, 08:34   #6
axer
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Not sure if a help, I remember that there was a different scope for wired clients rather than wireless clients. I believe wired clients defaulted to 8 days and wireless clients leased time was one day. Not sure if relevant here.
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07-02-2011, 13:59   #7
Static M.e.
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Do you really need the test server to hold the DNS & DHCP roles?

I dont think you will have a problem if you let the Wireless router do your DNS and DHCP.

If you want to play with DNS, you can always set it up on the WS2008 Server with a forwarder to the default gateway (Wireless router).

Last edited by Static M.e.; 07-02-2011 at 14:07.
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08-02-2011, 21:54   #8
rolion
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A DC has to be DNS for AD to work properly...
You can have the router as DNS/DHCP,but for dhcp the DC will detect that another DHCP running and will shut down.

Try from a wireless Windows client running "DHCP Explorer"utility and see where and what stops or filters DHCP request/offer traffic ! Do same with wired...

Do a factory reset of the router and re-configured by wizard and/or step-by-step !
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