====== MSSQL Reverse DNS ======

  * http://msdn.microsoft.com/de-de/library/ms190693.aspx

<code sql>
-- To allow advanced options to be changed.
EXEC sp_configure 'show advanced options', 1;
GO
-- To update the currently configured value for advanced options.
RECONFIGURE;
GO
-- To enable the feature.
EXEC sp_configure 'xp_cmdshell', 1;
GO
-- To update the currently configured value for this feature.
RECONFIGURE;
GO
</code>

  * http://www.holisticsystems.co.uk/blog/reverse-dns-lookup-ms-sql-server
<code sql>
declare @ip_address varchar(16)
declare @cmd varchar(100)
declare @host_name varchar(100)

declare curs cursor LOCAL READ_ONLY
--for select ip_address from ip_address_data where arp_domain is null
FOR 
SELECT DISTINCT AwLog.Host
FROM AwLog
	LEFT JOIN DNS ON DNS.Ip = AwLog.Host	
WHERE DNS.Ip IS NULL	
open curs

create table #output(line nvarchar(100))

while 1=1
begin
fetch next from curs into @ip_address
if @@fetch_status != 0 break

set @cmd = 'nslookup '+@ip_address

insert into #output
execute xp_cmdshell @cmd

--update ip_address_data set
--arp_domain = (select substring(line,10,99) from #output where line like 'Name%'),
--last_cached = getdate()
--where ip_address = @ip_address
select @host_name = substring(line,10,99) from #output where line like 'Name%'
print(@host_name)
INSERT INTO DNS (Ip, HostName) VALUES (@ip_address, @host_name)

delete #output

end

drop table #output
close curs
</code>