Duplicate DNS entry issue

Posted on 2009-12-21
Medium Priority
Last Modified: 2012-05-08
I am going through our DNS zone file and it is a mess.  There are tons of duplicate host entries and for some of the entries I am not certain which ones are actually valid.  What is an easy way to determine which of the entries are actually valid?  The only thing I could think of was dumping DHCP and dumping the zone file, combining them in Excel, sorting, etc.  Is there any easier way?
Question by:rufustmac
LVL 12

Accepted Solution

nsx106052 earned 1000 total points
ID: 26098059
I would start by turning on scavenging of stale DNS records and shortening your DHCP lease.  Your DNS server probably isn't removing old record so they keep building up.  After making the changes allow a few days for the old records to get removed.
LVL 57

Assisted Solution

giltjr earned 1000 total points
ID: 26098083
Do you have dns scavenging enabled?  If not, you may want to enable it.  Otherwise dumping DHCP and DNS may be the "easiest" way.

Expert Comment

ID: 26099414
It may be tedious, but you could also just ping each dual entry and see which one works, delete the other one.
LVL 57

Expert Comment

ID: 26100024
The problem with using ping is that you not only will have the same host name with more than one IP address, you may have the same IP address assigned to more than one host name.  So although the ping will respond, you don't know which host is returning it.

Author Closing Comment

ID: 31668627
We are going to just delete all the dynamic entries, turn the TTL down and turn on scavenging until everything is all cleared up.  Thanks.

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