DNS problems

[phreaqe]

i am not sure if this is the right forum for this so if it isnt please move it to the right location.

i am using server 2003 for our dns server at work. we have 2 domain controllers runing our dns and dhcp. the problem is that we have about 150 tablets all over the country that vpn in and synch with an sql database. they are set to automatically synch every hour. they need to synch on the hour to send us forms that have been filled out by patients.

the problem occurs in our dns server. we are having multiple entries show up for the same ip address in the forward lookup zone. i read that turning scavenging on will take care of this. it is on and set to every 2 hours. however we are still having this problem and it is becoming a realy hassle trying to deal with it. i noticed taht at a global setting(when i go to properties of the domain controller itself in the dnsmgmt console) it does not have scavenge stale records checked. does that override the setting for an individual zone? the zone says it is set to scavenge. any ideas? thanks in advance.
-Mark

 

[Smilin]

First, consider placing your DHCP server in the DNSUpdateProxy group. This will cause DDNS registrations by your DHCP server to leave records without an owner. The first time the RRs are updated the owner will then be set. This allows you to use DHCP DDNS registration but still let the client do it's own cleanup. It can reduce the number of duplicate names out there as clients can clean up their own RRs. Do NOT do this if your DHCP server is a domain controller. Otherwise someone can alter your DCs SRV records.

Second, scavenging will help keep things clean over the long term but it should not be expected to provide relief from duplicate entries right away. Do not get aggressive in scavenging in an attempt to correct this problem. You'll only end up scavenging good records and making a real problem.

Scavenging must be set in three places:
1. On the server. Configure ONE DNS server to do scavenging regardless of how many servers have a replicated copy of the zone. You set a scavening period on the server and this is how often it checks for eligible RRs to clean up.
2. On the zone. Here you set the no-refresh and refresh intervals. If you want more agressive scavenging, lower the no-refresh interval. I wouldn't fool with the refresh interval much. Keep these settings in "days". Don't fool with "hours".
3. On the individual record. A record must have a timestamp to be scavenged. To view this stamp, use the view | advanced option in the DNS MMC. Static records will not have a timestamp. Do NOT use the dnscmd ageallrecords...this will convert static records to dynamic and shoot a hole in your foot.

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The biggest source of confusion for people is knowing when scavenging will actually take place.

Go to the properties on a zone then hit the 'aging' button. See that timestamp at the bottom. Nothing is going to happen before then. Don't even bother trying to manually hit the "scavenge now".

Now go to the properties on a record. See that timestamp? Add the refresh and no-refresh intervals (per the zone settings) to this timestamp. This is when a record will be *elligible* to scavenge...it ain't gonna actually disappear at that time. If a records is elligible and the timestamp on that zone has passed then the next time the server does a scavenge (per server settings) the record will disappear.

Using default settings (7 day server interval, 7 day no-refresh, 7 day refresh) it is theoretically possible for scavenging to occur as early as 14days or as late as 21.

Hope this helps.

 

[phreaqe]

that is alot of information. thank you. i will try to sort through that and see waht i can do. this is not my area but since i work for a small company and it is jsut me and my boss right now till we hire a third person i am trying to make do with what i can. thank you for that info. i appreciate it.
-Mark

 

[Smilin]

I do DNS support at MS among other things. If you are new to all this I would recommend the Windows 2000 DNS white paper. There are only a few minor changes from 2000 to 2003 but there is no 2003 version of the docuement.

It's one of the best docs I've seen for ramping quickly on DNS.

A search should produce both Word and HTML versions.

 

[phreaqe]

Originally posted by: Smilin
I do DNS support at MS among other things. If you are new to all this I would recommend the Windows 2000 DNS white paper. There are only a few minor changes from 2000 to 2003 but there is no 2003 version of the docuement.

It's one of the best docs I've seen for ramping quickly on DNS.

A search should produce both Word and HTML versions.

Thank you. i will take a look at that. i need anything i can get to help me understand some of this stuff. i know how dns works in prinicipal bu ti have no idea how to manage it. thanks agian.