Static IP vs Dynamic IP

[robrpb]

I am upgrading my internet speed and with it comes a free upgrade for a static IP if I want it. What are the advantages and disadvantages of a static IP vs a dynamic IP? Thanks.

[Kareeser]

A static IP basically means that every time you reconnect to your ISP, you get the same IP address. Sort of like a permanent phone number. A dynamic IP is a temporary "phone number" the ISP gives you, and changes whenever you dial. That's the only difference.

They're handy for web servers and domains (something.com) because that name ties to the IP address of the server hosting the website. A dynamic IP just adds a layer of confusion.

In the end, however, if you're just a typical internet user browsing the internet, there's no advantage at all.

[bill_bright]

A dynamic IP is a temporary "phone number" the ISP gives you, and changes whenever you dial.

That assumes we are talking dial-up. If you are using broadband, you are always connected. If you lose connection (power outage, unplug cable/DSL modem), you may or may not get a new IP, depending on how long you were disconnected and how your ISP works. If you use a router, and everyone with broadband should, even with a single computer, your router will assume the IP assigned by the ISP - so even if you shut down your computer, the router will keep that IP. No problem because your router assigned a different IP to every computer connected to it.

In the end, however, if you're just a typical internet user browsing the internet, there's no advantage at all.

Well, there's one good advantage to a dynamic IP. Dynamic IPs are useless to bad guys (not an issue if behind a router).

[robrpb]

I have DSL and a Linksys WRT54G router. I would say that I am just a typical internet user.

[mairving]

Originally Posted by bill_bright If you use a router, and everyone with broadband should, even with a single computer, your router will assume the IP assigned by the ISP - so even if you shut down your computer, the router will keep that IP. No problem because your router assigned a different IP to every computer connected to it.

I think that you are confused between an external and internal (NAT) IP. The internal one will stay the same on the router but the external one can change, assuming a dynamic scheme.

You only need the static IP address if you plan on running a mailserver/webserver, etc., neither of which is a good idea with DSL/Cable. Security isn't really an issue since you wouldn't have any open ports unless you manually opened them. I would still take the fixed IP address. There may come a time when you might need it.

[Kareeser]

Um. I wasn't assuming dial-up in the slightest.

If the router drops the signal and automatically reconnects, the router will be assigned a different external IP by the ISP.

In which case, my telephone analogy works perfectly.

[bill_bright]

Originally Posted by mairving I think that you are confused between an external and internal (NAT) IP. The internal one will stay the same on the router but the external one can change, assuming a dynamic scheme.

No, I am not confusing internal and external. But you are right the external CAN change - that does not mean it will change as is implied here:

Originally Posted by Kareeser If the router drops the signal and automatically reconnects, the router will be assigned a different external IP by the ISP.

This implies if you disconnect even a cable/DSL modem, even for even a second, you will get a new IP. Not going to happen - at least not with broadband. There are all kinds of reasons why the ISP might lose connectivity to a cable/DSL modem for a couple seconds to several minutes. It would be a waste of resources to continually reassign IPs every time the power flickers. So network administrators set a time, often 300 to 600 seconds (5 - 10 minutes) or more (maybe less) before a new IP will dynamically be assigned to a given (and pre-authorized) MAC address - and if the ISP sees that MAC address within the set time, it simply establishes a connection with the same IP. This is why I said,

If you lose connection (power outage, unplug cable/DSL modem), you may or may not get a new IP, depending on how long you were disconnected and how your ISP works.

Dial up is different because (1) chances are you are dialing into a different modem on the other end each time, and (2) they don't care about your MAC address. So with dial-up, you get a new IP.

It is simple to test and see how your ISP's admin has it set up. Check you IP then unplug your Cable/DSL Modem. First for 10 seconds, then a minute, then 5, yadda yadda.