Hi All, so you’ve probably heard of goDaddy.com to register DNS names publicly. However have you ever done a dig or nslookup on your registered name? It probably returns the name you queryied and the IP address just as you expected, however this is because dig is by default recusive. This means that it will ask it’s known DNS server if it knows the DNS resolution for your query, if not, forward it on and on and on until it is found through the DNS hiearchy or it times out. See the diagram below.
DNS Hierarchy
Let’s walk through this.
- TLD (Top-Level Domains) — These are the highest level on the DNS hierarchy. You can find a list here.
- SLD (Secondary Level Domains) — These are they domain names you are most familary with, like google.com, slashdot.org, thejimmahknows.com. Notice each of there suffix’s
- Sub Domains — Logically grouped resources, such as mail.google.com and linux.slashdot.org. Can have multiple prefix subdomains (i.e. a.b.c.d.google.com)
- Resource Records — There are several different types. The most common are A reocrds, MX records, and CNAME records.