How to monitor DNS query response time
DNS (Domain Name System) servers translate standard language web addresses to their actual IP addresses for network access. DNS response time is the time it takes a Domain Name Server to receive the request for a domain name’s IP address, process it, and return the IP address to the browser or application requesting it. When it comes to DNS response times, the lower the better, and generally values less than 100ms are considered to be in the acceptable range (depending on the application).