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DHCP Lease and DNS refresh

Posted on 2006-06-15
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Last Modified: 2010-03-19
I would like to have some clear explanations about DHCP renewal interval and DNS reresh/No refresh interval.

How the setting of one affect the other?

I appreciate it.

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Question by:jskfan
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Accepted Solution

by:
bbrunning earned 250 total points
ID: 16912610
No-refresh interval
 An interval of time, determined for each zone, as bounded by the following two events:

1.  The date and time when the record was last refreshed and its time stamp set.
2.  The date and time when the record next becomes eligible to be refreshed and have its time stamp reset.
 
This value is needed to decrease the number of write operations to the Active Directory database. By default, this interval is set to 7 days. It should not be increased to an unreasonably high level, because the benefits of the aging and scavenging feature might either be lost or diminished.
 
Refresh interval
 An interval of time, determined for each zone, as bounded by the following two distinct events:

1.  The earliest date and time when the record becomes eligible to be refreshed and have its time stamp reset.
2.  The earliest date and time when the record becomes eligible to be scavenged and removed from the zone database.
 
This value should be large enough to allow all clients to refresh their records. By default, this interval is set to 7 days. It should not be increased to an unreasonably high level, because the benefits of the aging and scavenging feature might either be lost or diminished.
 
Taken from http://technet2.microsoft.com/WindowsServer/en/Library/92d228d2-4fe2-40b9-88a7-2a5a2bee85081033.mspx?mfr=true


Not quit sure what you're trying to learn here. Could you be a little more specific with your question?
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Author Comment

by:jskfan
ID: 16912789
If I understood:

DHCP lease by default is 8 days, and clients request renewal of the (same)IP address when they reach 50% of therir lease (4days).

let's say the lease started 06/01 through 06/08, on the 06/04 there will be renewal.
let 's say the no refresh and refresh in DNS are both set to 7 days

so the record won't be refreshed between 06/04/ through 06/11  7 days.
so the record can be scavenged betwee 06/11 through 06/18 if No Renewal has been initiated by the clients.

is this correct or off side?

is the lease renewal  initiated from the clients when requesting DHCP is what they call refresh in DNS?

please some clear explanations.

thanks



 
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Assisted Solution

by:Manhars
Manhars earned 250 total points
ID: 16917993
When a DHCP client starts up for the first time and has no lease, it begins in the INIT (initialize) state and goes through the allocation process described in the preceding topic to acquire a lease. The same process is used when a lease ends, if a lease renewal fails, or some error or other happening causes a client to need a new lease.
Situations Where Reallocation Is Performed

There are certain situations in which a client starts up while it still has a lease already in place. In this situation, the client does not need to go through the entire process of getting an IP address allocation and a new lease setup. Instead, it simply tries to re-establish its existing lease, through a process that I call reallocation.

There are two primary circumstances under which a client performs reallocation rather than allocation:
 Power On With Existing Lease: The length of time that a client lease lasts can range from minutes to years; it is entirely a matter of the lease length policy set for the network and client by the administrator. Many, if not most client machines are not left connected to the network 24 hours a day; they are turned on during the day and then shut down at night, and also shut down on weekends. A client with a very short lease that is shut down and then later started again will probably find that its lease has expired, and will have to get a new one. However, if a lease is longer than a few days, it will still probably be in effect when the client starts up again.
 Reboot: Clients are also sometimes rebooted, to install new software or correct a problem. In this case even when the lease length is very short, the restarting client will still have a valid lease when it starts up.

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Expert Comment

by:Manhars
ID: 16918004
Refresh determines the number of seconds between a successful check on the serial number on the zone of the
primary, and the next attempt. Usually around 2-24 hours. Not used by a primary server.
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Author Comment

by:jskfan
ID: 16919937
in our case we have aging and scavenging enabled in
- one DNS server and the zone
- and disbaled in another DNS server but enable in the same zone
 both DNS servers are  domain controllers in one domain.

We are getting duplicate IP address, duplicate DNS records.

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