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Do I have a permanent IP address?

  1. Apr 22, 2013 #1
    When I am on the internet, say using physicsforums, am I assigned a fixed IP address for my one computer? Or does it change from day to day??

    I was under the impression that my computer had some IP address assigned and it remained 'mine' as long as I had that computer. OR can I generally expect a new IP address after each shut down of my computer and restart the next day?
     
  2. jcsd
  3. Apr 22, 2013 #2

    harborsparrow

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    Generally, internet service providers "lease" you a temporary IP address, and the next time you reboot your computer, you may be assigned a different IP address. If you want a permanent IP address for your home computer, you would have to pay a substantial fee for that to the internet service provider (if they even allow it). However, there are proxy services that can be set up to find out what your IP address is today (your computer will need to contact the proxy each time it boots up and let the proxy database the latest IP address), and people can thus always find out (when working remotely) what the latest IP address of their home machine is.

    It used to be that my home PC would at least get an IP address in the same subnet each time it rebooted, but even that is no longer the case. Since I use some remote services at a university, they put firewall restrictions in place, and those differ depending on which internet provider I am using. So at the university, they have to track and know which address ranges Verizon or Comcast typically assign so that they can at a minimum double-check that I am connecting from one of those services.

    At workplaces, IT departments sometimes assign a permanent IP address for each machine in a database, so that each time the machine requests an IP address, it gets the same one. But even then, you can't count on having the same IP all the time unless you have requested that from whomever provides the internet.

    It is possible to rent a hosted computer from a service such as GoDaddy (I happen to use DiscountASP.NET as my host), and they will provide your hosted server with a permanent IP address (or the equivalent of one) so that you can have your own web server, just for example. It will cost you something, however.
     
  4. Apr 22, 2013 #3
    thank you....that's what I wanted to understand...
     
  5. Apr 22, 2013 #4

    jtbell

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    Isn't the external IP address actually assigned to your cable or DSL modem, with your computer having only a local IP address that gets translated to/from the external one by the modem?
     
  6. Apr 22, 2013 #5

    harborsparrow

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    When at home, that is technically correct; the internet provider gives the router an IP address. You can get a permanent IP address from your router by reconfiguring it and changing the settings on your computer; however, this local area network IP will not be visible beyond the local router.

    If you want to reach your computer when away from home, you'll need a couple of different strategies--one that sends the router's current IP address to the proxy database, and then you'll also need to know your local area network IP address assignment.

    Thanks, Jtbell, I had forgotten (sr. moment already).
     
  7. Apr 22, 2013 #6

    Borek

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    Google for "what is my IP" address and visit any of the sites found - it will tell you what is your IP address at the moment. Do it several times in 24 hours periods, are at least switching your modem on and off. If it is the same IP each time, you have most likely static IP.

    After checking our database it looks to me like you have a static IP, as most of your posts come from just a few IP addresses. Users with several kposts and using dynamically assigned IPs usually have hundreds of IPs addresses in our database (I am getting close to 1700).
     
  8. Apr 22, 2013 #7

    rcgldr

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    Both cable and DSL ISP offer "semi-static" ip's as an option if you want separate external ip's for each computer or ethernet device connected to your modem. Cable modems support up to 16 separate ip's, but my cable ISP provider only allows 3 ip's. DSL typically gives you 8 ip's, but 3 of those are overhead, so you end up with 5 ip's (you need a different type of DSL modem for this to work). In my case, the ip usually changes every few months.
     
  9. Apr 22, 2013 #8

    jtbell

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    Now that I'm home and can check the configurations of my network devices, it looks like I actually have two local networks.

    The DSL modem has two IP addresses: the "WAN IP address" which the outside world sees (verified by a web-based tool), and a local address 192.168.0.1.

    The modem connects via Ethernet to my main wireless router, which also has two IP addresses: 192.168.0.3 which is presumably what the modem "sees", and 10.0.1.1 which my other wireless devices "see."

    The devices that are currently using the wireless network all have similar addresses:

    main wireless router = 10.0.1.1
    second wireless router for extending the network = 10.0.1.2
    Apple TV = 10.0.1.3
    my Mac Pro = 10.0.1.5
    TiVo = 10.0.1.6
    printer = 10.0.1.10
     
  10. Apr 23, 2013 #9

    Borek

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  11. Apr 23, 2013 #10
    Borek posts:
    Duh, why didn't I think of that?? getting old I guess....

    I had looked in Wikipedia under IP ADDRESS but the information wasn't what I was looking for. The link to LOCAL NETWORK is better....until I read jtbell's post it had not occurred to me I had
    a web type IP address and a local network address....

    I happen to have three internet radio's linked to my modem plus a DVD recorder so little did I know I was a 'local network administrator' in my own house!!

    [An annoying aspect of IP addresses is when I reply to certain e-mails that seem outside my own Yahoo e=mail, I get asked for the 'ISP host' and what 'type' it is, I think!! I did manage to find the address and wrote it down, but never did figure the protocol type [my own perhaps inaccurate term].....for other 'computer dummies' like me, what you can do is just copy the address of the sender and paste it in your own e-mail....]

    Thanks a lot guys.

    Now for the bad news: I listened to a late night hysteric on 'Coast to Coast AM radio' [a late night news/discussion/sometimes science/sometimes aliens radio] a few weeks ago and the guest was all panicked about all the microwaves we get poisoning us...cell phones and [I had not thought about before] wireless routers in homes, and of course microwave ovens and power lines. I do wonder about people living near high voltage power lines. My daughter just got a new car...equipped with bluetooth which I have never used....but that's wireless too. I no longer have a boat but wireless connections have mad their way aboard as well. I'm guessing flat screen tv's have LESS emissions than older C RT sets?? so maybe we have made a bit of progress there, but the new sets are so much bigger....
     
    Last edited: Apr 23, 2013
  12. Apr 27, 2013 #11

    jtbell

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    Today I noticed that my wireless adapter (Apple Airport Express) was telling me that I had a "double NAT": two devices giving out local addresses via DHCP (the adapter itself, and the DSL modem). It suggested that I put it into bridge mode to remove the redundancy. I did so. After the network came back up I had a single set of local IP addresses of the form 192.168.0.x, given out by the DSL modem.

    Upon Googling a bit I discovered that double NAT can cause problems with certain network configurations or devices, but I hadn't noticed anything before. At least my network setup is a bit "cleaner" now.
     
  13. Apr 29, 2013 #12

    jtbell

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    Getting rid of the double NAT in my wireless network did cause some noticeable improvements, after all.

    Certain complex pages load better now. For example, with Google Maps, often some of the "tiles" in a map didn't load, leaving gray blocks on the page. And with cnn.com and some other sites, often a page would "hang" while loading, and I had to hit Firefox's "reload" button one or more times to get it to load completely. I thought it was because of my slow DSL connection, about 0.75 Mbps. But now those pages load properly the first time.

    When I transferred recorded TV programs from my TiVo to my computer for archiving, the speed would be only about 2 to 3 Mbps, and often it would "hang" part way through so I had to start over. Now I get about 6 Mbps, and so far (two programs) it hasn't "hung" yet.

    When I stream video from my computer to my Apple TV, it buffers noticeably faster than before. Video from the outside (e.g. YouTube) isn't affected because it's limited by the speed of my DSL connection.

    Double NAT must cause enough extra packets to be broadcast that it slows down or interferes with the flow of data.
     
    Last edited: Apr 29, 2013
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