Cannot access Internet

Posted on 2004-10-28
Last Modified: 2010-04-10
Hi Experts,

One of my user have a little problem. Sometimes he cannot access interent from LAN. I have to restart his machine everytime to get access for internet. We are using DHCP.
What is causing this problem any idea.
Question by:smaziz
    LVL 3

    Expert Comment

    Hi smaziz: Could you provide more info? ...
    OS, network info, firewall / proxy ... Under what circumstances does the machine hang, or does it reboot itself, or does Internet Explorer crash? What error msg do you get, if any? Are there any other symptoms that the same machine manifests, apart from Internet problems?
    LVL 2

    Expert Comment

    I would first check to see what his NIC config is by going to START- RUN- Type CMD, Press Ok.  Then type ipconfig in the prompt.
    One thing you might want to check if the host is configured with a static ip.  You can check with winipcfg from the CMD Prompt.  Also can check by checking the properties in the TCP/IP Configuration in NetNeighborhood.  I would also check to see:  How many hosts are on the LAN?  How many IP address are are available in the DHCP pool?  If there are too many hosts for the amount of IP addresses that would definitely be a problem.  To see if the problem is non-DHCP related, I would assign that host a static IP address that you know is valid and can access the internet.  From there, this should give you an idea of where the problem is.  Let me know how this ends up.

    LVL 15

    Accepted Solution

    Try to check if, on that pc´s Local Area Network, in the advanced tab, Power management, all options are uncheked. If not, unchek them, because they place the network card under powersaving method, and, therefor, it looses connectivity.

    Best Regards !
    LVL 4

    Expert Comment

    Once the Net connectivity is lost , then go to command prompt and give this command ipconfig. If u find an ip then, there should be no prob with the DHCP.try to ping the gateway ip to crosscheck the Net connectivity.If the ping status is okey then problem with explörer...try to repair or replace it ...... If u dont find the ip when u type ipconfig in the command prompt then then try to asign a static ip apart from the DHCP pool IPS.

    Other side u can check the DHCP ip pool range,aging  and any ip reservations........

    LVL 1

    Expert Comment

    Another thing to watch out for is how long the default lease is on the DHCP server and how good it is at freeing a lease when a machine isn't connected for a while.

    We used to get DHCP addresses given out by one of our routers, specifically for people roaming between sites using wireless connections from their laptops. However, the router would store the IP address it had given to a particular NIC for days, regardless of the lease timeout. If the lease had expired, the router would give out the IP to someone else, but when the person who had it before re-connected, it would assume that, as the IP already had a lease active, nothing needed to be given out to the new connection from a known NIC, even when it asked for an IP address. (This is quite hard to explain really, never mind to understand - it basically boils down to  some wierd software fault in the unit giving out the IP addresses). Only a router reset or repeatedly disconnecting and reconnecting the errant wireless client would clear the router's ARP cache and wake everyone's connection up again.

    I cured this by stopping DHCP being done by the routers and switching it to our Linux server. Took a bit of setting up to get it working as required, but we no longer have any problems with DHCP!

    So, my suggestion is - try to get another device/PC to do the DHCP to see if that cures the problem...

    LVL 1

    Expert Comment

    If anyone is interested you can make a batch file that runs daily. That releases and renews the ip address assigned by the DHCP Server. That is..... , if the power saving features that allow the Network card to go to sleep to save power aren't ticked.
    Or maybe try another nic as they only cost about $20.

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