Sudden ping spike

Sometimes pinging in cmd shows over 150 ms latency and around 35 ms for
Now two questions -

  1. Why do the latencies differ that much for and ? Does this mean i can use as primary dns due to comparatively low ping and use another dns ( maybe) as secondary ?
  2. While latencies are horrible while checking in cmd,when i go to it show an ip which on pinging shows 13ms ping.I dont understand which result to believe.