_ldap._tcp.dc._msdcs query causing client delays

[Eric Goldsmith]

My Win2K (SP4) laptop is an AD domain member and works fine on the
office network. However, when it's on my home network, many actions
result in a 15-20 second delay between the time the action is
initiated and executed.

These actions includes things like: staring IE, starting Media Player,
starting Windows Explorer, opening My Computer->Manage, etc.

A network sniff shows that during these delays, my laptop sends 5 DNS
queries for _ldap._tcp.dc._msdcs.<domain name>. They eventually all
time out, and life goes on.

From the research I've done, I learned these DNS requests result
because my laptop is trying to locate a DC. I can understand this
occurring during the login process, but why does it occur repeatedly
after login?

On my home network, the DNS server address handed out (via DHCP) to
clients is my router/firewall, which acts as a forwarder.

So, what can I do to eliminate these constant DNS queries and the
resulting delays?

Thanks,
Eric

 

[Kevin D. Goodknecht [MVP]]

In

My Win2K (SP4) laptop is an AD domain member and works fine on the
office network. However, when it's on my home network, many actions
result in a 15-20 second delay between the time the action is
initiated and executed.

These actions includes things like: staring IE, starting Media Player,
starting Windows Explorer, opening My Computer->Manage, etc.

A network sniff shows that during these delays, my laptop sends 5 DNS
queries for _ldap._tcp.dc._msdcs.<domain name>. They eventually all
time out, and life goes on.

From the research I've done, I learned these DNS requests result
because my laptop is trying to locate a DC. I can understand this
occurring during the login process, but why does it occur repeatedly
after login?

Anything you do that requires network access must be authenticated by the DC
that you have permissions for the activity.

On my home network, the DNS server address handed out (via DHCP) to
clients is my router/firewall, which acts as a forwarder.

This is probably your problem I suppose the router's DHCP is giving out the
router's address for DNS?
In an AD Domain you should not use any DNS but the AD DNS in any position.

So, what can I do to eliminate these constant DNS queries and the
resulting delays?

Use DHCP in Win2k it supports AD functions, and only use your local AD DNS
server on all machines NICs. Never an ISP's DNS anywhere except as a
forwarder in your local DNS server.
300202 - HOW TO: Configure DNS for Internet Access in Windows 2000
http://support.microsoft.com/?id=300202&FR=1

If this does not fix the behavior post back with your ipconfig /all and the
domain name in ADU&C.