DHCP IP Problems
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Thread: DHCP IP Problems

  1. #1
    Senior Member isle_of_infamy's Avatar
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    my real problem

    ok my real problem is that my IP will not renew when I ask it to. I used WNTIPCFG and also tried EZ-DHCP and even Multi Network Manager 7.1, but still it stays the same upon release/renew. why ?

    the WNTIPCFG indicates a 24 hour lease time on the IP number which would seem standard for most IP numbers, but even after I wait until the lease expires it still will not change.

  2. #2
    AO French Antique News Whore
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    Where do you get your IP from? ISP, Lan? What OS do you have? Help us help you!
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  3. #3
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    Because technically you need to contact your ISP about your IP address and if you want to change/renew/etc it.
    Space For Rent.. =]

  4. #4
    Senior Member isle_of_infamy's Avatar
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    Cox cable and I am on windows 2000 pro

  5. #5
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    Generally, broadband ISPs lease IPs out based on a MAC address. So barring changing your MAC, you probably can't change your IP. Until yesterday when I swapped a NIC out of my linux router here, our place had the same IP for over two years.
    Chris Shepherd
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  6. #6
    Senior Member isle_of_infamy's Avatar
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    for some reason my ip lease renews when i boot up my pc. thats why i cannot get it to change i think.

  7. #7
    Just a Virtualized Geek MrLinus's Avatar
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    for some reason my ip lease renews when i boot up my pc. thats why i cannot get it to change i think.
    You might want to do some research into the DHCP protocol. When you boot up and your network card/OS is set to use DHCP rather than a static IP, it will send out a broadcast request to find a DHCP server. In turn, upon hearing the request the DHCP server will respond and assign an IP address. As per chsh, it's very likely that if it finds the same MAC address as before it assigns the same IP as used before.

    RFC 1541: Dynamic Host Configuration Protocol (aka DHCP
    RFC 2132: DHCP Options and BOOTP Vendor Extensions

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  8. #8
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    Probably it is renewing correctly, but it is giving you the same IP address back.

    Nearly all DHCP servers will give your machine the same IP address back if you renew it. In fact, most of the time even if you allow it to expire and wait a while, you'll STILL get the same one back.

    DHCP servers try not to change anyone's IP address if they can avoid it. On networks with a very static number of machines (for example cable modems), IP addresses typically rarely change.

    There is nothing you can do to FORCE a DHCP server to hand out a new address - that's not what they do. The server tells your machine what address to use, not the other way around.

    A few DHCP servers can be configured with an inverse policy of the above, i.e. change IPs as *often* as possible, but it's not a normal configuration.

    Slarty

  9. #9
    Senior Member isle_of_infamy's Avatar
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    but i used to change it at freewill anytime i wanted. it was just recently that i was unable to change it.

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