PTR

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Proper DNS Resolution for non-dynamic addresses

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Scope

For certain types of static, user-added systems like firewalls, routers, switches, etc, you have to manually create the DNS entry. However, just creating a DNS entry does not complete the record. In the TPFND enviroment, it has been realized that even when the "Update associated pointer (PTR) record" is checked in the DNS record properties, the PTR itself is often not created. Therefor, for these devices, a PTR record must be manually created afterwards.

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Example

We have a Cisco 2960G switch that we manually created a DNS record for:

  • Host Name: 2960G
  • FQDN: 2960G.tpfnd.cat
  • Type: Host (A)
  • Data: 10.0.0.9

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Process

Open DNS Manager on your main DNS server Go into "Reverse Lookup Zones" Go into the correct in-addr.arpa folder (here it's 0.0.10-in.addr.arpa) Right-click in the main panel, choose "New Pointer (PTR)..." You will get a pop-up of "New Resource Record" In Host IP Address, add 9 after the last dot Click "Browse" next to the empty "Host name:" entry Select (double-click) the main DNS server Select (double-click) the "Forward Lookup Zones" Select (double-click) "tpfnd.cat" Scroll down to 2960G, click OK Leave "Allow any authenticated user to update" unchecked Click OK

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Verification

Before

In PowerShell, "resolve-dnsname 10.0.0.9" returned DNS name does not exist:

PS C:\> resolve-dnsname 10.0.0.9
resolve-dnsname : 9.0.0.10.in-addr.arpa : DNS name does not exist
At line:1 char:1
+ resolve-dnsname 10.0.0.9
+ ~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : ResourceUnavailable: (9.0.0.10.in-addr.arpa:String) [Resolve-DnsName], Win32Exception
    + FullyQualifiedErrorId : DNS_ERROR_RCODE_NAME_ERROR,Microsoft.DnsClient.Commands.ResolveDnsName

After

In PowerShell, "resolve-dnsname 10.0.0.9" returns a valid result:

PS C:\> resolve-dnsname 10.0.0.9

Name                           Type   TTL   Section    NameHost
----                           ----   ---   -------    --------
9.0.0.10.in-addr.arpa          PTR    3600  Answer     2960g.tpfnd.cat

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