[NTLUG:Discuss] "Back up dns server"?

[brian at pongonova.net]

On Wed, Dec 05, 2007 at 05:26:54AM +0000, Leroy Tennison wrote:
> "DNS round-robin"
> 
> Maybe I'm overly cynical but "DNS round-robin" sounds like an alias for 
> "Russian roulette" to me.  This technology is good for load balancing 
> but not so great for redundancy.  

I'd recommend familiarizing yourself with how DNS works then.

> A solution (but I don't know enough about how referrals work to know if 
> it is applicable, anybody really good with DNS who can answer this 
> question? - I'm not) may be at the DNS server lookup level.  DNS servers 
> are supposed to be able to handle recursion for clients.  A client asks 
> for server1.web.dept.company.com.  The DNS server doing the recursion 
> (assuming it isn't authoritative for for web.dept.company.com) looks for 
> servers that are authoritative for ".com" and gets a list (or has a 
> configured list).  It asks one of these servers for 
> web.dept.company.com, what happens if that server isn't available?  Does 
> it check the next one?  This isn't really DNS round robin if I 
> understand that correctly because I thought that technology only 
> referred to resolution of the actual DNS name (not intermediate DNS 
> servers along the way when trying to find the name).  If this works then 
> you don't need DNS servers with the same name or alias.  Both servers 
> are authoritative for the domain and should be supplied in a referral. 
> If referrals are checked until one replies then there's no problem.

Already established SOP. 

  --Brian