DNS A and PTR record errors

Discussion in 'Windows Small Business Server' started by Al Williams, Feb 14, 2008.

  1. Al Williams

    Al Williams Guest

    SBS2003 Sp2 Premium.

    I was looking in the DNS Manager and I noticed a few incorrect forward zone
    A records and reverse zone PTR entries in there. Some PC's were listed
    multiple times, some were missing. Some of the PC's that were wrong were
    laptops so I can see them moving about but other were not (some Win9X
    machines though).

    How is this list maintained? Does the DHCP service somehow inform DNS when
    the IP changes or what?
    Should I fix the errors, anything to worry about?

    Al Williams, Feb 14, 2008
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  2. Al Williams

    Joe Guest

    It can, but doesn't by default. You can enable it. I forget which
    service has the configuration, but it's not hard to find.

    anything to worry about?
    I don't think so, though occasionally there can be problems. I believe
    that almost all of the time, the search algorithm will find the most
    recent entry, which will be correct. This is often suggested as an area
    where obscure DNS problems can be fixed, but I'm not sure anyone has
    definite evidence either way. I think more problems are caused by DNS
    errors on workstations.
    Joe, Feb 14, 2008
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  3. Yes, but DHCP isn't always informed when a station stops using an address.
    If one just unplugs a laptop from the network, it has no opportunity to
    release its lease. Nor does a normal shutdown do that. (I recall there's
    some tweak you can do to release on shutdown, but don't recall details.)

    If DHCP isn't informed of the release, it won't delete the lease and its
    associated DNS records until the lease expires.

    Note that DHCP information is tied to MAC addresses. If a station changes
    MAC address (by changing network cards or using a different connector in a
    dual-NIC machine) then DHCP will assign it a different address.
    I'd recommend cleaning out stale information periodically. The DNS and DHCP
    systems may not know enough to know what's safe to remove.

    BTW, historically the microsoft.public.win2000.dns newsgroup has been the
    best source of Windows DNS server information. Were it not for the MS
    newsgroup server policy, I'd recommend cross-posting to that group.
    Kenneth Porter, Feb 14, 2008
  4. I just noticed there's an even busier newsgroup at
    Kenneth Porter, Feb 15, 2008
  5. Al Williams

    Al Williams Guest

    If DHCP doesn't populate the DNS then do the workstations do it? This may
    explain it as most of the bad entries are related to older Win98 machines.

    Al Williams, Feb 15, 2008
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