Questions

Some computers not updating new IP in DNS

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Some computers not updating new IP in DNS

mstry9
We have 2 DNS servers and randomly when we move a machine to a different VLAN, the DNS entry never registers the new IP.
The Microsoft support person had no answer.
Any suggestions would be appreciated, except switching to Linyx :)
  • +
    0 Votes
    3xp3rt

    Maybe you tried this, but if not, right click on Network Connection, and select Repair.

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    0 Votes
    mstry9

    We worked around it by removing them from Active Directory and re-adding them but I would like to find out what is causing it so we don't have to touch each of them when it happens.

    Thanks

    +
    0 Votes
    mstry9

    We worked around it by removing them from Active Directory and re-adding them but I would like to find out what is causing it so we don't have to touch each of them when it happens.

    Thanks

    +
    0 Votes
    mstry9

    We tried that, the machine did release and renew the ip address but the DNS issue remains.

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    0 Votes
    jamesatmaisonverre

    I dont think the problem is with the software but i think there is a problem with the routers or more probably the switches as your servers ip address is determined by this hardware.I work with this stuff everyday and it is usually faulty switches

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    0 Votes
    scott_heath

    Your DNS server must be set to allow updates from clients, it isn't automatic. Check you DNS server settings, it's called Dynamic DNS. Are you using 2000 or 2003 server?

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    0 Votes
    mstry9

    Our DNS servers are set to allow dynamic updates from secured clients only. Due to ou having a wireless network on campus wor the students to bring thier own laptops, we do not allow un-secured clients to update DNS records. I'll check with our System Engenier about the switch possibility but this only happens on about 3 out of every 20 new PC we add each month.
    I really appreciate everyones input on this as it's not mission critical, I just have different department heads asking me about it every month. I'd like to resolve it or explain why we can't.

    Please leave this thread open for now in case someone else has more input.

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    0 Votes
    CG IT

    if clients are DHCP clients and you move them from 1 VLAN to another, then when they go look for a DHCP server to get an address, that DHCP server needs to provide them with DNS servers to find a server to authenticate with. It's possible that the new VLAN they are moved to doesn't provide them with the right DNS server information. Depends on where they get the information from. If there are different DNS and DHCP servers on each VLAN, I can't see how this happens, but if the DHCP server is on another VLAN, it's possible the Relay agent doesn't do its job. As long as they are set to obtain IP and DNS automatically, shouldn't matter where you move them, they'll get their information from DHCP provided DHCP is configured correctly. IF you have AD I'd change from allow secure to active directory intergrated and then configure DNS to update associated records from clients.

    really need more detailed information on your network setup.

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    0 Votes
    mstry9

    Both internal DNS servers and the DHCP server are all on the same VLAN. We have about 12 VLANS in all.
    The DNS servers ARE Active Directory integrated and Dynamic updates is set to secure only?
    Are you suggesting we change them to nonsecure and secure. Would this not allow any wireless laptop to run the /registerdns and create an entry in the DNS table?

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    0 Votes
    CG IT

    you said your DNS was secure updates and I suggested if it's an AD to go to AD intergrated.

    VLAN is collecting switch ports into subnets. So you've got 12 subnets there, how is DHCP providing addressing? somewhere along the way in configuration, how the VLANs get their information is not providing your DNS server addresses.

    +
    0 Votes
    mstry9

    Sorry I misunderstood. The switch is indeed AD integrated. The DHCP server has several scopes and they are somehow linked to specific VLANS.
    I'll ask my Cisco Engineer to check the switch configurations, I do know that he has tested this issue with Cisco support and the maintain that it is not a problem with the switches.
    One more bit of info:
    This senerio sometimes happens on one of 2 or 3 machines that are conected to the same switch in the closet for that area.
    Would that not eliminate the switch as a source of the problem?
    Again, this is a great site and all of you have been very nice since I am a system admin here and only do basic things on the switches like open and close ports.

    +
    0 Votes
    CG IT

    I'm saying make sure the VLAN [software side of things] configuration is correct. Could be trunking isn't doing what it's supposed to be doing or STP. If you have 1 or 2 DNS servers that service the whole network, then both should be provided to clients via DHCP. DHCP providing VLANs with their subnet addresses should also provide DNS as well. IOS on the Catalysts has DNS entries as well as DHCP entries can can provide that to clients.

    So all I'm really saying is that whom ever configured IOS for the Catalysts should review VLAN configuration. The best way imo to solve the entire moving around problem is wireless. Setup a subnet for wireless and those that move use wireless instead of having to constantly move patch cables like the old days when operators patched phones to other phones.

    +
    0 Votes
    scott_heath

    Use ethereal or ms network monitor to capture packets as you try to update dns info and see what happens. Might help if you know where the packets are trying to go. You can monitor at the server end to see if they ever get there and what the server does.

    +
    0 Votes
    mstry9

    At this point I'm turning this infrequent and random issue over to my System Engeneer.
    I've showed him all these helpful suggestions but assures me he has worked with Cisco on this and all of these tips are in place or have been tested. I did learn some things about how VLANS work with DNS and DHCP so much thanks indeed.
    As a bonus, my department director has set aside a cisco switch that I can play with and become more adept at working with.

    Happy Holidays to you all and again,
    Thanks

    Michael

  • +
    0 Votes
    3xp3rt

    Maybe you tried this, but if not, right click on Network Connection, and select Repair.

    +
    0 Votes
    mstry9

    We worked around it by removing them from Active Directory and re-adding them but I would like to find out what is causing it so we don't have to touch each of them when it happens.

    Thanks

    +
    0 Votes
    mstry9

    We worked around it by removing them from Active Directory and re-adding them but I would like to find out what is causing it so we don't have to touch each of them when it happens.

    Thanks

    +
    0 Votes
    mstry9

    We tried that, the machine did release and renew the ip address but the DNS issue remains.

    +
    0 Votes
    jamesatmaisonverre

    I dont think the problem is with the software but i think there is a problem with the routers or more probably the switches as your servers ip address is determined by this hardware.I work with this stuff everyday and it is usually faulty switches

    +
    0 Votes
    scott_heath

    Your DNS server must be set to allow updates from clients, it isn't automatic. Check you DNS server settings, it's called Dynamic DNS. Are you using 2000 or 2003 server?

    +
    0 Votes
    mstry9

    Our DNS servers are set to allow dynamic updates from secured clients only. Due to ou having a wireless network on campus wor the students to bring thier own laptops, we do not allow un-secured clients to update DNS records. I'll check with our System Engenier about the switch possibility but this only happens on about 3 out of every 20 new PC we add each month.
    I really appreciate everyones input on this as it's not mission critical, I just have different department heads asking me about it every month. I'd like to resolve it or explain why we can't.

    Please leave this thread open for now in case someone else has more input.

    +
    0 Votes
    CG IT

    if clients are DHCP clients and you move them from 1 VLAN to another, then when they go look for a DHCP server to get an address, that DHCP server needs to provide them with DNS servers to find a server to authenticate with. It's possible that the new VLAN they are moved to doesn't provide them with the right DNS server information. Depends on where they get the information from. If there are different DNS and DHCP servers on each VLAN, I can't see how this happens, but if the DHCP server is on another VLAN, it's possible the Relay agent doesn't do its job. As long as they are set to obtain IP and DNS automatically, shouldn't matter where you move them, they'll get their information from DHCP provided DHCP is configured correctly. IF you have AD I'd change from allow secure to active directory intergrated and then configure DNS to update associated records from clients.

    really need more detailed information on your network setup.

    +
    0 Votes
    mstry9

    Both internal DNS servers and the DHCP server are all on the same VLAN. We have about 12 VLANS in all.
    The DNS servers ARE Active Directory integrated and Dynamic updates is set to secure only?
    Are you suggesting we change them to nonsecure and secure. Would this not allow any wireless laptop to run the /registerdns and create an entry in the DNS table?

    +
    0 Votes
    CG IT

    you said your DNS was secure updates and I suggested if it's an AD to go to AD intergrated.

    VLAN is collecting switch ports into subnets. So you've got 12 subnets there, how is DHCP providing addressing? somewhere along the way in configuration, how the VLANs get their information is not providing your DNS server addresses.

    +
    0 Votes
    mstry9

    Sorry I misunderstood. The switch is indeed AD integrated. The DHCP server has several scopes and they are somehow linked to specific VLANS.
    I'll ask my Cisco Engineer to check the switch configurations, I do know that he has tested this issue with Cisco support and the maintain that it is not a problem with the switches.
    One more bit of info:
    This senerio sometimes happens on one of 2 or 3 machines that are conected to the same switch in the closet for that area.
    Would that not eliminate the switch as a source of the problem?
    Again, this is a great site and all of you have been very nice since I am a system admin here and only do basic things on the switches like open and close ports.

    +
    0 Votes
    CG IT

    I'm saying make sure the VLAN [software side of things] configuration is correct. Could be trunking isn't doing what it's supposed to be doing or STP. If you have 1 or 2 DNS servers that service the whole network, then both should be provided to clients via DHCP. DHCP providing VLANs with their subnet addresses should also provide DNS as well. IOS on the Catalysts has DNS entries as well as DHCP entries can can provide that to clients.

    So all I'm really saying is that whom ever configured IOS for the Catalysts should review VLAN configuration. The best way imo to solve the entire moving around problem is wireless. Setup a subnet for wireless and those that move use wireless instead of having to constantly move patch cables like the old days when operators patched phones to other phones.

    +
    0 Votes
    scott_heath

    Use ethereal or ms network monitor to capture packets as you try to update dns info and see what happens. Might help if you know where the packets are trying to go. You can monitor at the server end to see if they ever get there and what the server does.

    +
    0 Votes
    mstry9

    At this point I'm turning this infrequent and random issue over to my System Engeneer.
    I've showed him all these helpful suggestions but assures me he has worked with Cisco on this and all of these tips are in place or have been tested. I did learn some things about how VLANS work with DNS and DHCP so much thanks indeed.
    As a bonus, my department director has set aside a cisco switch that I can play with and become more adept at working with.

    Happy Holidays to you all and again,
    Thanks

    Michael