How does dns scavenging work

If you have it run every 7 days and the no refresh is 7 days and the refresh is 7 days you are 21 days out. And what do i need to do when i have multiple DHCP scopes with different lease periods? DNS Scavenging will only remove records based on their timestamp. DNS scavenging will not remove statically configured records. These are records manually created or changed from DDNS to static. You can see below my DHCP1 server has a timestamp and is not static.

I will need to fix this. Check all your server records and change them to static before moving onto the next step. Open the DNS Console 2. Right Click on the zone you want to enable scavenging on and click properties 3. Click the Aging button 4. It only takes a few minutes and may save you from a headache or two down the road.

In most cases, as long as the device is powered on and connected to your network, this registration process will occur roughly every 24 hours, keeping the dynamic record fresh and active in DNS. From time to time, we admins will set up static records. These can be simple host A records for a device like a network printer or copier.

These could be SRV records for servers like Exchange. A static record can be created for just about anything. At a high level, the aging process compares the age of a DNS record to that of refresh and no-refresh interval values you configure.

If the record is older than the aging values, the scavenging process purges it from DNS. If not, the record remains. However, DNS Aging and Scavenging can be configured to process static resource records in addition to dynamic resource records. If you registered a new record days ago, as far as DNS scavenging is concerned, the record is days old, and will be purged.

How often you do this is up to you and should be based on the number and frequency of changes you make to your network. The values you choose are up to you and your environment. If you simply select the defaults, 7 days no-refresh and 7 days refresh, a DNS record has the potential to age to 14 days old before becoming stale.

If your scavenging period is set to the default setting of 7 days, the records are purged only once a week. Your DNS record can now exist for a period between 15 — 20 days. The no-refresh interval means the timestamps on your DNS records cannot be refreshed.

In order to remove a stale resource record automatically, you must enable the scavenging on the resource record, the DNS zone where the resource record exists, and at least one DNS hosting a primary copy of the DNS zone where the resource record exists.

Right click on the Zone you want to enable scavenging on and click on the properties as shown below:. Click on the Aging button. You should see the following screen:. You can adjust the interval settings with your desired value. Right click on the DNS server and click on the properties. Hopefully our screenshots and notes made you an expert at understanding DNS Scavenging and Aging and help you with configuring it easily!

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