DNS Scavenging Settings

[ba9ag]

Hi

 

Id like to setup up DNS scavenging as I can see there are a few duplicate entries but I'm a bit confused as to what the settings should be. Microsoft defaults to and recommends having a DHCP lease time of 8 days (which works well with us) and the Microsoft articles suggest a No-Refresh Interval of 7 Days and a Refresh Interval of 7 Days. From reading the articles on here though a lot of people say the sum of these figures (14) should not be greater than the DHCP Lease (8) if I'm reading it correctly? Can onyone shed some light on this. I also see there is a tickbox to enable automatic scavenging of records and again this defaults to every seven days. Would be interested to hear from anyone who can recommend the settings required if the DHCP lease is set for 8 days. Thanks

[albertwt]

Hi

 

Id like to setup up DNS scavenging as I can see there are a few duplicate entries but I'm a bit confused as to what the settings should be. Microsoft defaults to and recommends having a DHCP lease time of 8 days (which works well with us) and the Microsoft articles suggest a No-Refresh Interval of 7 Days and a Refresh Interval of 7 Days. From reading the articles on here though a lot of people say the sum of these figures (14) should not be greater than the DHCP Lease (8) if I'm reading it correctly? Can onyone shed some light on this. I also see there is a tickbox to enable automatic scavenging of records and again this defaults to every seven days. Would be interested to hear from anyone who can recommend the settings required if the DHCP lease is set for 8 days. Thanks

 

I do strongly recommend going for Aging / Scavenging. It's just would rather you avoid a 1 hour refresh It will kill every dynamic record for every system with a static IP every time automatic scavenging runs.

 

I normally advise things are set like this, the DHCP Lease is an example value only, not a suggestion (here for context):

 

DHCP Lease: 16 days

 

No-Refresh: 4 Days

Refresh: 4 Days

Automatic Scavenging: 1 Day

 

The total record age is equal to 8 days here, which is half of the DHCP lease. That's because DHCP leases are extended by multiples of the Renewal Interval, and that is 50% of the DHCP lease.

 

With those settings your static systems would be happy, plenty of time to update records, and your DHCP clients would be happy.

 

All that remains is figuring out if you how more than one DHCP server in the mix.

 

 

HTH