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I'm interning at a company, and it seems like the DNS is really screwed up. There are a bunch of cases where multiple IP addresses are assigned to the same machine in the reverse lookup zone section, and multiple machines are assigned to the same IP in the forward lookup zone section. Is this normal? I feel like it's really messed up and should be fixed. If anyone has any suggestions on how to fix this, please let me know, any help would be appreciated.

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3 Answers

Have you made sure that DNS scavenging is turned on? It'll process the records and delete the old ones on a regular schedule.

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+1 You got me on the scavenging bit :) –  squillman Oct 22 '09 at 19:53
    
It's enabled in the forward lookup zone but not the reverse, so should I enable it for the reverse lookup zone and change the intervals for the forward lookup zone? Right now, the no-refresh interval and the refresh interval for the forward lookup zone are both 7 days. –  shawn Oct 22 '09 at 20:15
    
7 days is the default. And you do want to scavange both forward and reverse lookup domains. –  sysadmin1138 Oct 22 '09 at 20:28
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Are these client machine records that are being autocreated? If so check that DNS scavenging is enabled.

Multiple machine names in the reverse zone can be perfectly normal in an environment where machines with multiple IP addresses exist. I'd question that for client/workstation addresses, though.

It's not uncommon to see multiple host records for the same IP in the forward lookup zone. Aliases (CNAMEs) should be used instead, though. Again, this is not typical for client/workstation addresses.

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This is perfectly normal for servers, especially ones that are doing several jobs such as hosting several websites, one per address.

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The problem is that it's the workstations that have all these multiple records in DNS, not the servers –  shawn Oct 23 '09 at 14:23
    
Sounds like it might be the legacy of a change in ISP and rather than renumber workstations, they just added new IP addresses and left the old ones in place too? –  Michael Dillon Oct 23 '09 at 21:22
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