Is there any way to block DNS request for single word queries?

Hi Experts,

 

I have a BIGIP DNS running as a DNS resolver for internet users. I found there are some DNS queries coming in and ask for records for names like a random string... such as dfsdfsdfsdf gfgdfgdfgrter...

 

Obviously this doesn't make any sense... but my GTM will still ask root server against these random string queries...

 

Is there any way to block/drop such DNS request? If it's iRule, could you please provide an example to show how such requests can be blocked?

 

Thanks!