Recently I came across a book on Ethical Hacking. One of the chapters talk about DNS as follows:
"A DNS Server is basically a server running DNS software. The server that the browser first looks for a translation is the Primary DNS Server, if this doesn't show any match, then it contacts another DNS server somewhere on the Internet, or the Secondary DNS server. If a match is found on the Secondary server, then the Primary server updates its database so that it doesn't have to contact the Secondary server again for the same match."
I was under the impression that the browser will contact the Primary DNS Server and if the DNS Server is alive and not able to resolve the name, the browser will not contact the secondary DNS Server as the primary DNS server is running. The secondary DNS server is contacted only when the primary DNS server is down due to some reason.
After reading the above quoted paragraph, I am in a little bit confustion.
Please comment on this.
MVP (Enterprise Security), ISLA-2010 (ISC)², C|EH, C|HFI, CCNA, MCP,
Certified ISO 27001:2005 Lead Auditor
[b]There are 3 roads to spoil; women, gambling & hacking. The most pleasant with women, the quickest with gambling, but the surest is hacking - c0c0n