ARCHIVED: What are some IP addresses that might indicate I have a network problem?

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A computer needs an IP address to use the Internet. Not all IP addresses give you connectivity. At Indiana University, to determine what range your computer's IP address falls within and whether it is problematic, use the following lists. For more information about finding an IP address, see Find your computer's IP address

Working IP addresses

At IU, the following IP address ranges are the ones your computer should fall within:

For IU Bloomington

  • Standard registered DHCP or static address ranges (in other words, the normal address you get unless you fall into one of the next two categories):
    • 129.79.x.x
    • 149.159.x.x
    • 156.56.x.x

  • Pre-registration (before registering for DHCP; for further details, see Register your wired device on the IU network):
    • 10.7.x.x
    • 10.10.x.x
    • 10.11.x.x
    • 10.12.x.x
    • 10.232.x.x

  • Wireless (before connecting to VPN):
    • 10.231.x.x
    • 10.235.x.x

Note: An "x" in an address (e.g., 129.79.x.x) stands for any number between 0 and 255.

For IUPUI

  • Standard registered DHCP or static address ranges (in other words, the normal address you get unless you fall into one of the next two categories):
    • 134.68.x.x
    • 149.166.x.x

  • Pre-registration (before registering for DHCP; for further details, see Register your wired device on the IU network):
    • 10.134.x.x
    • 10.148.x.x

  • Wireless (before connecting to VPN):
    • 10.60.x.x
    • 10.235.x.x

Note: An "x" in an address (e.g., 129.79.x.x) stands for any number between 0 and 255.

If you don't get an address in any of the above ranges, then either you're not on the IU network, or you have a connectivity problem.

Problem IP addresses

Following are some addresses that indicate a problem with your connection:

  • 169.254.x.x: This is what's called an Automatic Private IP address. An IP in this range means that the computer cannot see the network. A computer using DHCP needs to have an external server tell it what IP address to use. Unfortunately, if there's no network connectivity, the computer is unable to talk to the server. In those cases, the computer will actually give itself an IP starting with 169.254, since it must assign itself some sort of number. When you see a 169.254.x.x address, you definitely have a problem. It could be as simple as an unplugged network cable, or it could be as complex as the network being down. A fair amount of troubleshooting is involved at this point, but the bottom line is that your computer doesn't even see the network.
  • 0.0.0.0: An IP address of all zeros means that your computer can see the network, but something else is interfering with its ability to get an IP address. To resolve this, you can try the following:
    • Temporarily disable or reconfigure the firewall: Some firewalls, especially older ones, are not intelligent enough to adjust to certain networks. The firewall may end up blocking your computer from the DHCP server. If you can configure it to allow the DHCP server for your network to communicate, then do so. Otherwise, try disabling it temporarily until either you've isolated and fixed the problem, or (if the firewall has proven to be the problem itself) you've learned how to configure the firewall for your current situation.
    • Make sure your network adapter is installed correctly: You can look in the Device Manager (Windows) or System Profiler (Macintosh) to make sure the Ethernet card is listed and functional. You should also check whether the proper driver is installed.
    • Ensure that DHCP is enabled on your computer: Make sure the setting labeled Obtain an IP address automatically is selected. On a Windows NT, 2000, or XP computer, also make sure the setting Obtain DNS server address automatically is selected as well. On a Macintosh, make sure the setting labeled Using DHCP (Mac OS X) or Using DHCP Server (Mac OS 7.6 through 9.x) is selected.

  • 192.168.x.x, 172.16.x.x, or 10.x.x.x: IP addresses in this range are called internal or private addresses. For more information, see Reserved ranges for private IP addresses

    Note: Before determining a problem associated with a private IP address, you need to know the exceptions. See the information on private IP addresses below.

Private IP addresses

At IU, the following private IP address ranges are in use:

For IUB

  • 10.7.x.x
  • 10.10.x.x
  • 10.11.x.x
  • 10.12.x.x
  • 10.232.x.x
  • 10.231.x.x (wireless)
  • 10.235.x.x (wireless)

For IUPUI

  • 10.134.x.x
  • 10.148.x.x
  • 10.60.x.x (wireless)
  • 10.235.x.x (wireless)

The addresses above (except the ones labeled "wireless") are assigned when you need to register your computer for DHCP (see Register your wired device on the IU network). The ones labeled "wireless" are assigned when you're making a wireless connection, prior to connecting through VPN.

Excepting the addresses above, having a private IP address can simply mean your computer is going through a home router or a proxy, or is connecting through another computer running Internet Connection Sharing (ICS). If this is the case, and you're doing it on purpose, then having a private IP address is fine. But, if you're not purposely going through a router, proxy, or ICS-enabled computer, getting a private IP address is bad.

If you're connecting in campus housing or in most places on campus, you are definitely not supposed to be going through a home router, proxy, or ICS computer, and getting a private IP address is bad (excepting, again, the ones listed above). It means that either someone has installed such a router without permission, or someone's computer is running ICS by mistake. Your connection may work fine, but it's likely it will be very slow or very restricted as to where you can go. If you are on campus and ever get a private IP address that's not in the range of exceptions noted above, contact your campus Support Center. For more information about this case, see About rogue DHCP servers on the IU network

Note: Some departments use private IP addresses to secure servers or workstations with sensitive data. In those cases, getting such addresses is fine. However, most people on campus should be getting full, legitimate addresses. Here's how you know you're supposed to get a private IP address (all of these apply only on campus):

  • You're using one of those restricted computers mentioned above, and you or your administrator has explicitly set it up that way.
  • Your computer is not yet registered for DHCP, and you're getting a 10.10.x.x, 10.12.x.x, or 10.56.x.x address.
  • You're using wireless, and you're getting a 10.231.x.x or 10.235.x.x IP address.

If you don't fit in one of those categories, you're not supposed to be getting a 10.x.x.x, a 192.168.x.x, or a 172.16.x.x IP address while on an IU campus.

This is document aoyj in the Knowledge Base.
Last modified on 2018-01-18 14:04:11.

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