title: Checking CName for several website - Allowed?
body: <p>I saw the below program for getting CNAME for any passed hostname using java
  <a href="https://stackoverflow.com/questions/20394696/how-to-get-the-canonical-name-of-a-hostname-in-java">How to get the canonical name of a hostname in Java?</a></p>
  
  <p>Assume I have a dictionary of 0.2 million words which could be possible subdomain of a given host.
  Now I run the program (in the above link) in a loop for each of this 0.2 million words to find valid subdomain without any sleep(If CNAME exist then its valid).</p>
  
  <p>My question is that:</p>
  
  <p>1) Is this allowed to check on such a huge wordlist? If no what is the maximum request i can check safely.</p>
  
  <p>2) Can it cause any issue to the server?</p>
  
  <p>3) Should i induce some sleep after like 10000 record check?</p>
  
  <p>I saw several tools which are using bruteforce to get subdomains and i think all were using same strategy.</p>
  
  <p>I tried to search in google but could not get answer for this.</p>
  
  <p>Thanks a lot in advance :)</p>