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

[Chris Cox]

m m wrote:
> All:
>  
> We all know that we need to have two DNS server for a domain.

Yes.  One needs to be functioning.... which is why you want two.

> Usually, these two DNS server have the same A records for a domain.
> All of this settings are preventing the web site (mail...) failure.
>  
> Based on the concept above, I think we should be able to set the 2nd DNS server to a different IP with same domain name as primary DNS server.

Of course.  You have two DNS servers, one a master and one a slave.  They both
serve up the same records and are authoritative for the same zones.

This is the norm.

> In this case, there is a need to run 2 servers with same domain but different IP. 
> Why is doing this?  When one of the IP is not available, another one will be still available.

I guess I'm  not understanding what you are saying.  Two DNS servers, each with different
IPs serving up records for the same "domain".... again, this is typical.

$ host -a -t ns ntlug.org
Trying "ntlug.org"
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 61619
;; flags: qr rd ra; QUERY: 1, ANSWER: 2, AUTHORITY: 0, ADDITIONAL: 2

;; QUESTION SECTION:
;ntlug.org.                     IN      NS

;; ANSWER SECTION:
ntlug.org.              13818   IN      NS      ns2.pmichaud.com.
ntlug.org.              13818   IN      NS      ns1.pmichaud.com.

;; ADDITIONAL SECTION:
ns1.pmichaud.com.       172216  IN      A       38.119.121.196
ns2.pmichaud.com.       172216  IN      A       74.200.74.45

Received 107 bytes from 127.0.0.1#53 in 0 ms

ns1 and ns2 both are authoritative for ntlug.org and have
different IP addresses... again, this is the norm.

>  
> Please note, this is not a web farm issue. I think this will be to fix IP (or firewall) "broken" issue.  
>  
> Am I right? Any company doing such a "back up DNS server"?

I'm either confused or just not understanding what the issue is.
Every company with a domain has multiple name servers with different
IP addresses serving up records for their domain.