Completely confused about the whole IP address thing

Discussion in 'Mac OS X Server, Xserve, and Networking' started by timmy toad, Nov 4, 2012.

  1. macrumors newbie

    Joined:
    May 2, 2011
    #1
    Firstly i have to tell you that i am trying to help a fella with a Win XP tower whose wired internet connection has just gone down, although his wife's Windows wireless lap top is ok, i changed the cable, so i suspect it is his Ethernet card. To confirm it is his Ethernet Card, i am now trying very hard to learn about IP addresses !!!.

    On my MacBookPro i have found what i thought was my lap tops IP address (in Windows you type in IPCONFIG)
    i type that into my browser window and get NOWT
    why is that ?, what am I doing wrong please ?

    I thought i would see my routers control panel at the very least ??

    Tim
     

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  2. macrumors 68000

    roxxette

    Joined:
    Aug 9, 2011
  3. timmy toad, Nov 4, 2012
    Last edited: Nov 4, 2012

    thread starter macrumors newbie

    Joined:
    May 2, 2011
    #3
    Nah, sorry, that did nothing either !!!, DAM DAM DAM !

    I have NOW found it, the slip of paper with my Password stuff on it

    192.168.1.254

    BUT why is that different to what my MAC tells me it should be ?

    Tim
     
  4. macrumors 68000

    roxxette

    Joined:
    Aug 9, 2011
    #4
    Mate your mac list the ip of the computer not of the router; never seen a default router at .254 lol
     
  5. thread starter macrumors newbie

    Joined:
    May 2, 2011
    #5
    It is very slowly getting clearer in my mind just what is going on !, thanks for your help roxxette.

    How about this for proof that my last number is 254 :-
     

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  6. macrumors 68000

    roxxette

    Joined:
    Aug 9, 2011
    #6
    Weird stuff :p sometimes whe have the answear infront of us lol
     
  7. nebo1ss, Nov 4, 2012
    Last edited: Nov 4, 2012

    macrumors 68000

    Joined:
    Jun 2, 2010
    #7
    .254 is one of the most common addresses for the router. Ipconfig is a windows command you use in a terminal window. There is an equivalent on the mac open a terminal window and type ifconfig.
     
  8. macrumors 68000

    roxxette

    Joined:
    Aug 9, 2011
    #8
    Op next time you find yourself in the same situation but without the slip under the router just google the brand and type "default" ip; if for some reason someone changed it just reset the device.
     
  9. macrumors 68030

    jared_kipe

    Joined:
    Dec 8, 2003
    Location:
    Seattle
    #9
    I'm lost, how did we get from 'trying to prove some ethernet card is bad' to 'what is the IP address of the router?'?

    It is rare for an ethernet card to go bad. Much more common something happened on the software side of things. Check the driver, check if the computer is getting an IP address from DHCP, if it has a self assigned address, or if it has a manual IP address. Check to make sure the subnet mask is correct, check to make sure the default gateway (router) is set right.

    Check to make sure the cable is seated and the lights are blinking.
    Check in BIOS that the device is enabled (if it is an on the motherboard NIC). BIOS may also be able to tell you if it thinks a cable is connected and how long it is.

    ----------

    That isn't necessarily proof.
    1) http:// infront of it simply indicates that there is a web administration panel on that IP address by default. A single device can have more than one IP address, its possible the router only runs the administration panel on that one.

    2) Thats the factory address, it could have been changed by a user.

    That said, you're probably right. But the only real way to see if that is the right gateway/router IP is to configure a client computer with that as its default gateway and see if you have access to the internet (or whatever network segment it is supposed to be routing to)
     
  10. macrumors 6502

    Joined:
    May 16, 2011
    Location:
    Orpington, Kent, UK
    #10
    Good call, I've had a few NIC's go bad at work, mainly through power surges.

    On a typical home network, the router is the 'centre' of the network. It uses a service called DHCP to assign an IP address to a particular machine. No two machines can have the same IP address.

    In the photos you've posted, your router has the .254 IP address, and the Mac has the .96 address.

    If there is no HTTP server running on .96, then you won't get anything come up. What you need to do is find the IP address of the hard-wired computer. When you get this address (it won't be .96 or .254), you have to 'ping' that address.

    To do this on a Mac - open Terminal, and type 'ping XXX.XXX.XXX.XXX'.
    To do this on a Windows machine - open command prompt and type the same command.

    Only if you type in the routers IP address...

    By the way - you will have a number of entries...
    IP Address - The unique IP address on the network of your machine
    Subnet Mask - This tells you the subnet the machine is on (typically a class C - 255.255.255.0)
    Gateway - The IP address of where traffic should go to - on a home network, usually the router address (on your network this should be 192.168.1.254)
     
  11. macrumors 6502a

    Joined:
    Sep 10, 2012
    #11
    RE: arp -a...

    Hi,

    Sometimes the Terminal command:

    arp -a

    can be useful for matching MAC addresses to DHCP assigned IP addresses to DNS assigned DNSes (host names).

    Switon

    P.S. The Bonjour Services tab of the Wi-Fi Diagnostics app will also show you all zeroconf devices potentially also including your router and Windows PCs.
     
  12. macrumors regular

    Joined:
    Jan 12, 2009
    Location:
    London
    #12
    actual ARP matches MaC addresses to IP addresses, it has nothing at all to do with names, that is dealt with by DNS
     
  13. thread starter macrumors newbie

    Joined:
    May 2, 2011
    #13
    Hey lads, i only just got notification of your replies, sorry about the delay in responding.
    I am taking all your replies on board, make no mistake, thanks for your input i am simply being ery slow in putting all your suggestions into pratice.
    I am thinking now itll be best to bring the darned thing home with me, wether he likes it or not LOL

    Tim
     
  14. macrumors 68000

    roxxette

    Joined:
    Aug 9, 2011
  15. switon, Nov 6, 2012
    Last edited: Nov 6, 2012

    macrumors 6502a

    Joined:
    Sep 10, 2012
    #15
    RE: the "arp -a" command, MAC addresses, IP addresses, and DNS names...

    Hi assembled,

    Yes ARP matches MAC addresses to IP addresses, but the Apple "arp -a" command, at least in my hands, also provides the DNS names when running a DNS server too, as you will notice in the following execution on my laptop when at home:

    > arp -a
    servertc.math.home (10.0.1.1) at xx:xx:xx:xx:xx:xx on en0 ifscope [ethernet]
    laser.math.home (10.0.1.9) at xx:xx:xx:xx:xx:xx on en0 ifscope [ethernet]
    mybook-01.math.home (10.0.1.50) at xx:xx:xx:xx:xx:xx on en0 ifscope [ethernet]
    appletv.math.home (10.0.1.55) at xx:xx:xx:xx:xx:xx on en0 ifscope [ethernet]
    kutta.math.home (10.0.1.60) at xx:xx:xx:xx:xx:xx on en0 ifscope [ethernet]
    server.math.home (10.0.1.20) at xx:xx:xx:xx:xx:xx on en0 ifscope [ethernet]

    where I have obscured the MAC addresses for security reasons. So, as you can see, the DNS hostname is matched to the host's IP address and to the host's interface MAC address.

    Switon
     
  16. thread starter macrumors newbie

    Joined:
    May 2, 2011
    #16
    Howdy folks, thank you for your continued help, i can VERY happily report that i have NOW fixed it, a lot easier than i EVER imagined LOL.
    I got it home and did the basic stuff with IPCONFIG and PING and found they gave perfect results, which immediately pointed to a Software issue, so i did a System Restore and perfect result, the Internet connection was immediately restored.

    Tim
     

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