When we visit a website system will read the DNS cache in the domain name corresponding to the IP address, you can not find the time when the system will find the hosts file, if not, will request a DNS query to the DNS server, DNS server will return the domain name
corresponding to the IP, use the IP address to access your system after receipt resolve the address, while the local DNS resolver cache to cache.
PS: If you can not resolve DNS address, or the address is wrong DNS cache, generally will use ipconfig / flushdns to clear all the DNS cache.