07 Sep 2016

Notes: DNS basics

Some notes regarding DNS for future reference, after watching DNS for developers - Maarten Balliauw session

  • DNS is just a phone book to translate host names to ip addresses
  • DNS holds different type of records. Using TXT record allows to store almost anything
  • Never use public hotspot WIFI DNS servers
  • Reduce the TTL before making changes to DNS records
  • DNS query results are cached everywhere
  • Simple DNS failover / load balancing
  • AWS (Route53) and Azure allows to monitor the IP addresses and update the DNS records so you get better failover / load balancing

Very interesting for my projects the last section of the talk regarding service discovery.

Useful commands:

    dig A www.example.com +trace

    nslookup www.example.com

    # flush dns cache on OSX

    sudo dscacheutil -flushcache; sudo killall -HUP mDNSResponder