HTTP Request for n number of urls

I have 500+ Url need to check whether it is working…Now I am using Http Request to full fill the requirement…Now I am facing issue that …For some URL the Url is working fine when I check manully ,when I Preview with the HTTp request I am getting as status code 0

Is it happening for random urls while running or specific urls everytime

Not working for service now URL

Mostly getting good response only for few URL its not working…Especillay Silva service now is not working