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Frequent DNS requests

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by shanghai sam

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I am running SBS 2000 with Active Directory, DHCP, DNS, Exchange 2000 and SQL 2000.
We have 2 NIC's - 1 for the the internal LAN and 1 set up to access our ISP via a router on an ISDN dial-up account.
Reviewing our ISA logs we have a regular dial-up to our ISP which has only occured as a result of introducing the router and does not happen when using the ISDN Terminal Adapter. All of our 15 Win2k client workstations are switched off during silent hours and the ISA logs still records many UDP requests on Port 53 to and from the ISP DNS Servers at all hours. ICMP using Channel 3 also occurs as a dial-up connection on a rugular basis?
Our external NIC is set up as follows:

IP: 62.231.138.22
Subnet: 255.255.255.255
Default Gateway:62.231.138.21 (router)
DNS1: 195.216.16.129
DNS2: 195.216.16.65

The internal LAN uses the SBS 2000 IP address as DNS1 and 195.216.16.129 as DNS2.
We do not have NETBIOS enabled (it is also blocked on the router). Exchange does not use any POP3 accounts and this option has been switched off. I have tried changing the frequency of DNS updates but this does not appear to make a difference.

Please help since our phone bill is showing average connections of around 8 calls per hour.

Many thanks,

Alan Strevens

4 replies

by william jay

Internet Explorer can and does "Update Subscriptions on a Schedule", and Outlook Express can check mail according to a schedule too, check where the requests are going to . . .

by vh_s

Might come due to your DHCP setting, although I'm not so sure.

Why not try to set a longer duration for the DHCP lease. Default is 3 days, that means that after 1.5 days, renegotiation will begin to establish a new lease. Make it 7 days and try it out.

Subnet is also strange as remarked in answer 1.

For the internal LAN, using one DNS should be sufficient instead of defining 2 DNS. You would need only the IP address of the SBS 2000 for the internal LAN DNS.

vh_s

by maxwell edison

When a router is in use, but is not configured to forward requests (default port: 80) or FTP server requests (port 21) problems may occur. When you setup your DNS Services Account, just specify how frequently you want your IP address to be updated.

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