DHCP Lease Expire Time (IPV4)?

Question

Could someone tell me what this does? I assume it changes my WAN IP address? Recently somebody got my WAN IP address and for security reasons I wish to change it, should I wait till the DHCP lease expires or should I call and ask someone to change it? Is there a way to shorten the time of the lease? I have Comcast by the way

Answer 1

DHCP Lease Expire Time (IPV4)? Could someone tell me what this does?

Lets start with DHCP what DHCP does. In very simple terms it comes down to this:

• New device does a DHCP req ("Hi, I am new here! This is my serial number. Someone please give me all the information needed to get on the local network")
• DHCP server: "Hi new device. Here are the settings you asked for. Feel free to use them for up to X hours." (For ease, lets say for up to 24 hours)

Now there are a few options:

1. "New device" uses these settings for up to 24 hours. After that it knows there are no longer valid (and may even be handed out to any other device who asks for them, so they should no lober be used). It can ask again like in the first paragraph. It might get the same data as it had before, or it may get a different answer. That different answer will be a valid answer to access the local network, but if the IP changes some other things like file copies over the network may break.
2. Or "New device" may way a while. Say 12 hours (half of the time in the first paragraph", and then think "Maybe I should ask for an extension to the lease, so it is valid for another 24 hours".

The 24 hours in this example is the DHCP lease time.

I assume it changes my WAN IP address?

Assumign that you have the following setup:

Desktop --- Router --- Internet
        1  2      3    4   

Then usually no: DHCP in this case is most likely used between 1 and 2. And that is your LAN and not to WAN.

If you are logged into the router and the router happens to use DHCP rather than DSL, or .... then maybe.

Maybe because you can configure a DHCP server to always hand out the same IP to a certain serial (MAC) number. And then you will always get the same answer.