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Win 7 DHCP Oddity

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  • LAN
  • Networking
Last response: in Networking
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July 30, 2012 9:51:18 PM

Hi

I am a qualified systems/networking engineer with over 40 years computing experience.

I install Satellite Connections for many different ISPs for many home users. System uses a Gilat Satellite Modem which is configured by a range of ISPs to provide a static IP adress to the downstream PC/Router which may be connected. Most installations are just a single PC, usually WIN 7 Home Edition.

My own HP Netbook (Win 7 32 Home) is configured (very standard) to automatically get IP address from the Satellite Modem DHCP - AND IT ALWAYS DOES. Please understand this point as it is important.

About 70% of all PCs encountered refuse to work unless the IP configuration is manually entered. I generally specify it in the Alternate settings and it ALWAYS then works. (In all these installations my Win 7 Netbook automatically connects.)

I have read many postings regarding this issue and have tried most of the solutions, but none work.

Most of my customers PCs have previously been (automatically) connected to another service and worked fine.

I am convinced this is a Win 7 DHCP issue.

Does anybody have any new suggestions that have worked to solve this problem ???

Thanks guys.



More about : win dhcp oddity

July 30, 2012 10:10:45 PM

When it doesn't work (DHCP), what does the TCP/IP configuration typically show (using ipconfig)? 169.254.x.x? 192.168.1.x? Blanks? Is it consistent?
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July 31, 2012 2:51:48 AM

Consistent standard 192.254.x.x
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July 31, 2012 3:12:45 AM

eibgrad said:
When it doesn't work (DHCP), what does the TCP/IP configuration typically show (using ipconfig)? 169.254.x.x? 192.168.1.x? Blanks? Is it consistent?



Consistent APIPA 192.254.x.x

Thanks
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July 31, 2012 3:24:22 AM

What about the subnet mask, 255.255.0.0? 255.255.255.0?

Does it have a default gateway (e.g., 192.254.x.1), valid DNS server(s), or will these be blank?
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July 31, 2012 4:12:55 AM

eibgrad said:
What about the subnet mask, 255.255.0.0? 255.255.255.0?

Does it have a default gateway (e.g., 192.254.x.1), valid DNS server(s), or will these be blank?



Not sure about the mask and gateway or DNS - will have to check at next installation. I suspect that the gateway/DNS will be blank
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July 31, 2012 8:52:13 AM

What I suspect (or at least initially suspected) was that each client was using DHCP by default, but a DHCP server didn't respond (for some as yet unknown reason), so finally the PC self-assigned an IP and subnet mask (what's known as an APIPA address). But that would normally be 169.254.x.x/16, not 192.254.x.x/16. And I would expect the default gateway and DNS servers to be blank.

So at this point, it remains unclear what's happening.
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