DHCP lease question

Hello, i reopen a thread similar to one else of mine becouse some thigns are stillunclear to me:

ill try keep in mind that a lease is actually an expiration date, it makes it clear this way.

But i wanted to tell you that almost every night i shutdown my pc and still have the same ip address even if powered down 3-4 days.

Why my ip address has't be given to someone else the time i had y comp closed?

So its not static, its not dynamic, is it mapped(assigned by ISP's dhcp a

But the differnce betwewen static and mapped is that mapped is a static reserved assignment by dhcp with an infinite lease(expiration date). But doesn that make it static also?

But then again i didn't pay for a static one!

Also i would like to ask what the real purpose of having an expiration ip address date since if we have the pc on for days the lease will get renewed and renewed all the time.

Reply to
Nicky
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Because your ISP has enough IP addresses to allocate one per customer. So there is no need to share any individual IP address between two or more customers.

The only difference is that you can't assume that your IP address will always be the same. But it probably will be. It may change once every few years when your ISP reconfigures their network. If you pay for a static one then you _can_ assume that your IP address will always be the same.

Because if you don't leave it on then when the lease expires the DHCP server will know that your IP address is not presently required by you and is available for someone else. If there were no lease time then the DHCP server might never know this. Not all customers leave their equipment on all the time and some customers will just disappear from a house address and stop paying without telling the ISP. With DHCP the ISP will reclaim the IP address a lot quicker than they might have otherwise. This does NOT mean it will definitely be given to someone else because there may be enough addresses to cover other customers, so your address will be kept for you and reassigned to you when you next come back online.

Some years ago the average customer spent far less time online and it was not easy for an ISP to have one IP address per customer. So it made sense to use dynamic allocation to share a number of IP addresses with a larger number of customers because you only needed to cover the maximum number of customers online at any one time. These days people have broadband and spend much longer online, many will have equipment online all the time, and it has become esier to get enough IP addresses to cover all customers even if they are not all online. Addresses are still assigned by DHCP to most customers but there are few reasons for a customer's IP address to change.

Jason

Reply to
Jason Edwards

I've been following this thread, even though I don't understand half of it

I have a home network with 2 XPHome and 1 WinME machine connected to a wireless router, I connect to the router through ethernet cable and the other XP and ME machines wirelessly. All machines are shut down each night and rebooted in the mornings, all machines keep the same private IP forever given out by the router. The router keeps the same MAC address but the IP number does change every so often, sometimes it will stay the same for a couple of weeks sometimes it changes within a few days of being given, in fact it changed the other day from one which had been in force for about a week. As I said I don't understand this networking stuff very well but thought I'd tell you my experience Joan

Jas>> Hello, i reopen a thread similar to one else of mine becouse some

Reply to
Joan Archer

Perfectly normal :)

Also perfectly normal. The policy of the ISP, the lease time, the number of customers per IP address that the ISP has, the structure of the ISPs network, whether or not you leave your router on, the price of your service and many other things can all influence whether or not and when it changes.

Jason

Reply to
Jason Edwards

Reply to
Joan Archer

you're doing great Joan! -- good procedure :-)

Reply to
Jeff B

Then be happy. Most people are paying extra money to get this behaviour.

Yours, VB.

Reply to
Volker Birk

Thank you very much Jason!

Now its all perfectly clear for me! :-)

Reply to
Nicky

So what i understand of all these i this:

This all may look that i have a static ip address but actually i havent because i didnt pay for one.

If i had a static ip addresss that would mean that my ISP would actually reserved an ip address for my personal use only but still through dhcp configuration manner at their end by setting an infinite lease time and not by remotely configured one or pre-attached one to my router when they send it over to me(is this possible btw? :-). They cant just manuallly attach an ip address to my router the way i attach one to my local NIC.

What the isp actually does in my case is that upon my first connection he logs my router's wan interface mac address and then associate it to a dynamic ip address that is available from an ip address pool! That way the ISP can remember what i used last time, so it can give me the same ip address next time i will reconnect in case of me disconnecting/powered down or having network problems so my connection dropped int he first place.

So, i have a dynamic ip address through dhcp assignment manner and it remains the same, confusing as as being static :-), not because it is static but because the ISP has so many ip addresses that he wont care if its 1:1 (1 specific ip address for 1 specific customer). The only way i would lsoe this address would be due to a ISP's pool change oder or a network reconfiguration.

Is this correct? I hope it is because iam fighting 3 days now for this :-)

ps: Oh, and the lease time is actually an expiration time :-)

Reply to
Nicky

very good. The sole point of this post is: your IP address may be reassigned in the interval you release (via ipconfig /release_all or power down your modem) ... some time interval allowing someone else to acquire a new DHCP IP address you power-on the modem or use ipconcif renew

Reply to
Jeff B

Not necessarily. When my broadband connection was installed the engineer had a sheet of paper telling me what IP address to use. This has a major advantage in that if I change my kit the ISP does not have to do anything.

Actually, it could well be your router remembering what address it had before and asking if it can have the same one again. Your ISPs DHCP server sees that no one else has it and gives it to you.

Or they could choose to force you to change address just because they felt like it. Or if you change your HW you might end up with a different address.

You don't really need to worry about this in any case unless you are offering services.

Effectively.

Reply to
Flash Gordon

=CE=9F/=CE=97 Flash Gordon =CE=AD=CE=B3=CF=81=CE=B1=CF=88=CE=B5:

So youa re tellign me that in case of static ip assignement we ourselves configure our router to sue the ip address that isp picked for us? No dhcp server assignement in isp's end?

How you know? It might as well be the isp's dhcp server the remembers what i had uses in the past because it might keep a record of mac address/login dyanmic ip address.

Yes but only in case that the isp associate the mac adrrees to dynamic ip address and not the login to ip adress or in case as you said above of my router remembering the last one ip used, this the new have no way of knowing.

Well, i just wont to understand how thsi works :-)

Canw e say that what differientates a static ip assignment of a syanmic one is that the first has an infinite lease time while the 2nd one has limited one? (provided that the assign works by remotely dhcp configuration).

Reply to
Nicky

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