O$ - Determine if machine is using DHCP

Alex Clay aclay at mac.com
Fri Apr 3 16:56:08 EDT 2009

On Apr 3, 2009, at 4:02 PM, CLIFFORD ILKAY wrote:

> Hash: SHA1
> Alex Clay wrote:
>> On Apr 3, 2009, at 2:17 PM, Doug Easterbrook wrote:
>>> out of interest, why does it matter (or whats the business  
>>> purpose) of
>>> how the machine gets its ip?
>>> you can get static addresses from DHCP bound to a mac address or
>>> dynamic ones.
>> It matters if you want to detect that your user is running DHCP on  
>> their
>> database server and advise them against that practice (causes  
>> headache
>> re-configuring clients with the server's IP changes).
> It wouldn't matter if you had DNS on the network and pointed the  
> clients
> to the host name rather than the IP address of the db server. DNS was
> invented to deal with that very problem.

Agreed, but how exactly do you automate installing a DNS server on the  
PC of a user who has low technical experience? And what about  
configuring network devices to use this DNS server? (Those are  
rhetorical questions.) We face this similar challenge with our user  
base. I'm hoping ZeroConf technology (a.k.a. Bonjour) is a better  
solution to this problem. It promises to allow us to find devices on  
the network near-instantly through human-friendly names and doesn't  
require re-configuring the client's network to do so.

> As Doug pointed out, you could
> also provision the same IP address to a given host based upon the MAC
> address. When we set up a network, typically, there is only one  
> machine
> with a static IP address, the machine that is serving dhcp requests.
> Every other machine on the network can and should be
> dynamically-assigned, even if we're assigning the same IP address to
> them every time.

True, but many small offices use consumer-level routers that function  
as DHCP servers. Having the user map static IPs to MAC addresses is a  
bit of challenge even when the router provides a "user-friendly" web- 
based configuration page. Neither administering a DNS server nor  
storing MAC addresses in a DHCP server are what I'd consider a turn- 
key out-of-the-box solution that "just works".


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