DNS name resolution slow - the first time...


M

Mik

I've configured 2 Windows 2003 DNS servers in a single forect/domain -
they are set to IP Forwarding to recursive name servers given by my
ISP. When I go to the cmd line and ping yahoo.com - the delay is about
4 seconds - thereafter its quick. The Domain controllers (2) are the
(ADI) DNS servers (2). I currently have 4 forward lookup zones - the
larget having 100 records. On the advanced tab of DNS the following
settings are used

Advanced tab:
Bind secondaries
Enable round robin
Enable netmask ordering
Secure cache against pollution

There currently exists a 2 way trust between the old NT4 domain and the
new win2003 domain. The new win2003 DCs/DNS do point at itself for
WINS as well as the NT4 WINS servers (qty2).

The configuration of the 1 NIC on the Windows 2003 DC is:
IP address x.x.x.100 static
DNS: x.x.x.100
WINS: x.x.x.100
x.x.x.50 (NT4 wins)
default settings for everything else

Internal private network is NATed - internal domain is false TLD
(mydomain.local)

Name resolution is slow on the client (clients only point to internal
AD DNS servers) as well as from the server.

Also.. heres a quick test from NSLOOKUP

Default Server: server1.xyz.local
Address: 10.10.10.100
yahoo.com
Server: server1.xyz.local
Address: 10.10.10.100

DNS request timed out.
timeout was 2 seconds.
*** Request to server1.xyz.local timed-out



Any assistance someone could lend in finding the source of the slowdown
would be greatly appreciated.

Mike
 
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K

Kevin D. Goodknecht Sr. [MVP]

Mik said:
I've configured 2 Windows 2003 DNS servers in a single forect/domain -
they are set to IP Forwarding to recursive name servers given by my
ISP. When I go to the cmd line and ping yahoo.com - the delay is
about 4 seconds - thereafter its quick. The Domain controllers (2)
are the (ADI) DNS servers (2). I currently have 4 forward lookup
zones - the larget having 100 records. On the advanced tab of DNS
the following settings are used

Are you behind a firewall? What Make and Model?
Are you using a forwarder?
What's the forwarder timeout?

Some firewalls block UDP packets over 512 bytes (EDNS0), which Win2k3 DNS
uses, if the external server doesn't respond using UDP the DNS server will
try again using TCP which is only limited by the MTU causing a delay the
first time. (Until the TTL expires then it will delay again)

Also, make sure any forwarders you use can do recursive lookups. Though, I'm
not too sure a non-recursive forwarder is the issue, because that will log
an error in the DNS event log.

Make sure you have port 53 UDP & TCP open outbound to any location, so DNS
can use recursion.

828263 - DNS query responses do not travel through a firewall in Windows
Server 2003:
http://support.microsoft.com/default.aspx?scid=kb;en-us;828263&sd=RMVP


--
Best regards,
Kevin D. Goodknecht Sr. [MVP]
Hope This Helps
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