Quick and Dirty DNS Testing

Quick and easy sanity checks…

My requirement was to test 500 A/PTR records.  The client didn’t feel comfortable with bulk loading the records, so the work had been split up to be manually added between multiple resources – I was concerned, and didn’t have much time to find the errors.

Process followed:

  1. Save a file containing all your IP’s
  2. Save a file containing all FQDNs
  3. Run the following from windows cmd:

FOR /F %i in (txt) DO nslookup %i >> resolutions-ip.txt 2>> failures-ip.txt

FOR /F %i in (.txt) DO nslookup %i >> resolutions-fqdn.txt 2>> failures-fqdn.txt

  1. Go have coffee and think how clever you are
  2. Realize that this could actually be scripted properly in Python and realize how clever you aren’t

This quickly gave me a great list of missed records from STDERR.  The duplicates and mismatched records were confirmed with some regex magic in notepad++ on the STDOUT output.

3mins work for pretty good yield, but if it’s a repetitive task (it wasn’t for me… yet…), script it properly!

Tagged , , ,

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

Collaboration Engineer

All things Technology - Posts to save for when you need them

Gerry Keleghan's Blog

A Blog about Cisco Unified Communications


my personal journey to ccie collaboration

Striving for greatness

Thoughts on DevOps, emerging tech, and open source

Network Experts Blog

“Knowledge comes by eyes always open and working hands.”

SIP Adventures

A unified communications blog by Andrew Prokop

The Cloverhound Blog

Cloverhound Employees Talk Unified Communications and Contact Center


Fog navigator. Get out of the clouds. Down to earth solutions. @Warcop

Cisco Collab Engineering Tips

Michael White - CCIE #26626


Photography by Manos,


Thoughts and experiences of a Cisco Collaboration engineer after clearing the CCIE lab...

The Daily Post

The Art and Craft of Blogging

The WordPress.com Blog

The latest news on WordPress.com and the WordPress community.

%d bloggers like this: