Bulk Adding Entries in DNS

While we are on the topic of bulk changes—I’ve discussed bulk changes in Active Directory and bulk adds to a WINS server—I thought I might discuss bulk adds of resource records to a DNS zone.

There are two pieces to the formula for bulk adding records to a DNS zone. First, we’ll reuse the for /f command used in automating the addition of entries into WINS. This time we’ll couple it with the dnscmd.exe tool from the Windows Server 2003 Support Tools (this link is for the 32-bit SP1 tools).

The format of the dnscmd.exe tool to add a record in DNS is:

dnscmd <server> /RecordAdd <zone> <node> <RR type> <RR data>

To create a host (A) record, the actual command would look like this:

dnscmd . /RecordAdd example.net host1 A 10.20.30.40

The “.” syntax here refers to the local server; this can be easily substituted with an IP address or hostname of a remote DNS server.

Using some of the same techniques as before, combining dsncmd.exe with the for batch command allows us to do something like this:

for /f "tokens=1,2" %1 in (newhosts.txt) do 
@dnscmd dns.example.net /RecordAdd example.net %1 A %2

This assumes that the “newhosts.txt” file contains something like this:

host1 10.20.30.40  
host2 11.22.33.44  
host3 12.24.36.48

Here’s a small twist, though: What if your list isn’t space delimited, but comma delimited? No problem, just adjust your command accordingly:

for /f "tokens=1,2 delims=," %1 in (newhosts.txt) do 
@dnscmd dns.example.net /RecordAdd example.net %1 A %2

The “delims=,” parameter tells the for command to use a comma as the delimiter, allowing us to use comma-separated input.

With this command, we now can pretty easily add large numbers of hosts to a DNS zone file.

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