My suggestion to all your problems is to use a public DNS server..
Oftentimes, your PC's DNS were given by your Internet Service Providers (ISP), so i assume that it is their DNS server... or if you're in an office, your Primary DNS Server's address were provided by your administrator..
To ease things up during lookup, try changing either of the Primary DNS Server or the Secondary DNS Server to a public DNS Server address such as this one:
208.67.222.222, or
208.67.220.220.
Remember, DNS Servers are used to translate Domain names to their IP address. If the DNS server you are using doesn't have the information yet (or oftentimes refreshed or re-cached) for the domain you are asking, such as
www.sonsivri.com, it will definitely take some time before it could resolve the actual IP address by asking other top-level DNS servers. By using Public DNS servers, you'll get faster response time and hassle-free name-to-IP translation