Install namebench from google to test dns response on Centos yum install tkinter wget https://storage.googleapis.com/google-code-archive-downloads/v2/code.google.com/namebench/namebench-1.3.1-source.tgz tar xvfvz namebench-1.3.1-source.tgz cd namebench-1.3.1 ./namebench.py It should automatically start like this: namebench 1.3.1 - best source (automatic) on 2016-08-29 17:00:06.588538 threads=40/2 queries=250 runs=1 timeout=3.5 health_timeout=3.75 servers=11 ------------------------------------------------------------------------------ - Reading Top 2,000 Websites (Alexa): data/alexa-top-2000-domains.txt (0.7MB) - Reading Cache Latency Test (100% hit): data/cache-hit.txt (0.1MB) - Reading Cache Latency Test (100% miss): data/cache-miss.txt (0.1MB) - Reading Cache Latency Test (50% hit, 50% miss): data/cache-mix.txt (0.1MB) - Reading Mozilla Firefox: /root/.mozilla/firefox/e3z6bpz8.default/places.sqlite (10.0MB) - Generating tests from Mozilla Firefox (68 records, select