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IOL DHCP Problem

  • 17-07-2004 8:18pm
    #1
    ZENER
    Registered Users, Registered Users 2 Posts: 6,163 ✭✭✭


    Strange one this - If I was to configure a range of addresses for a DHCP server I would normally avoid addresses that begin with "0"

    i.e. 192.168.0.0

    or ending in 255

    i.e. 192.168.0.255.

    For the past week I've been having problems connecting to some sites
    - timing out etc - while other users have no problem connecting. This came to a head last night when trying to get info from a site I knew was up. I checked firewalls, routing tables, proxy server addresses, - everything but no difference. Then I noticed my i.p. address was xxx.xxx.xxx.0. I rebooted my router a few times to obtain a new address not ending in "0" and all was ok again. The sites I was having trouble with were fine again !!

    Is it normal for ISP to dole out IP addresses like this ?
    Why do some sites not answer requests from these addresses ?

    ZEN


Comments

  • #2
    halenger
    Hosted Moderators Posts: 2,094 ✭✭✭halenger


    As far as I know it's a bug. I've suffered this problem before. Unfortunately IOL don't reset your IP with ever disconnect anymore so I had to force an IP on my router, luckily I found one that wasn't in use, and I had the internet working again.

    It's a royal pain. .0 and .255 are special IPs are aren't supposed to be used anywhere, from my networks studies.


  • #3
    tomk
    Registered Users, Registered Users 2 Posts: 1,067 ✭✭✭tomk


    Unbelievable.

    You would expect your ISP to know a little about this stuff, wouldn't you?

    XXX.XXX.XXX.0 is the network address, and XXX.XXX.XXX.255 is the broadcast address of the network. Neither of them will work as client addresses.


  • #4
    nosferatu
    Closed Accounts Posts: 9 ✭nosferatu


    .0 and .255 are network and broadcast addresses for /24 networks, with classless subnetting IOL don't necesserally have to dole out IP addresses from blocks of /24s.

    Whether or not that's a good thing I'm not sure It does increase the number of addresses they can use, but it's possible other networks filter out .0 and .255 assuming they are broadcast traffic from a class C network. This could be what zener is seeing.


  • #5
    Moriarty
    Registered Users, Registered Users 2 Posts: 6,007 ✭✭✭Moriarty


    Could be nosferatu. Windows sometimes breaks when its assigned .0/.255 as an ip though, so it could very well just be that. In any case, it's not one of the smartest things iol have ever done.

    Your best bet Zener is to just keep releasing the ip until you get a non- .0/.255 address, which is a pain.


  • #6
    ZENER
    Registered Users, Registered Users 2 Posts: 6,163 ✭✭✭ZENER


    As I said things are fine now but I was surprised at the IP address I'd been given and the varied effects it had.

    Thanks for the replies lads - maybe there is some other poor sod out there who is having the same problems as I did and he may happen across this post.

    ZEN


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