Dig Understanding DNS Master Preparation-Aquan's Den

DNS resolution is generally authorized more than two, to prevent a single point of failure.

For example, Aquan's study domain name www.aslibra.com, authorized two
Ns.aslibra.com and ns2.aslibra.com, what if a single point of failure?

Trace Check the domain name:

[Email protected] ~]# dig www.aslibra.com. +trace
.... (Omit partial query)
aslibra.com. 172800 in NS ns.aslibra.com.
aslibra.com. 172800 in NS ns2.aslibra.com.
;; Received bytes from 192.48.79.30#53 (j.gtld-servers.net) in 199 ms

www.aslibra.com. A 222.76.215.25
Aslibra.com in NS ns.aslibra.com.
Aslibra.com in NS ns2.aslibra.com.
;; Received bytes from 219.232.241.83#53 (ns.aslibra.com) in 8 ms

That is, 83 of the server returns information. To close the 83 service, we will check again:

[Email protected] ~]# dig www.aslibra.com. +trace
.... (Omit part of the same query)
www.aslibra.com. A 222.76.215.25
Aslibra.com in NS ns.aslibra.com.
Aslibra.com in NS ns2.aslibra.com.
;; Received 124 bytes from 219.232.241.84#53 (ns2.aslibra.com) in 7 ms

This time it was 84 that the request was processed.
This indicates that the individual can not respond to the next processing, to increase the NS authorization needs in the superior application, that is, in the COM. Apply for more than one NS record, their own designation seems useless, because the superior authorized two, two official authorized servers are all hung up is no longer able to query.

Let's do an experiment:

Increase NS3 's authorization:

[Email protected] ~]# dig www.aslibra.com +trace
.... (Omit part of the same query)
www.aslibra.com. A 222.76.215.25
Aslibra.com in NS ns.aslibra.com.
Aslibra.com in NS ns2.aslibra.com.
Aslibra.com in NS ns3.aslibra.com.
;; Received bytes from 219.232.241.83#53 (ns.aslibra.com) in 2 ms

After turning off NS and NS2, NS3 is actually useless:

[Email protected] ~]# dig www.aslibra.com. +trace
.... (Omit part of the same query)
aslibra.com. 172800 in NS ns.aslibra.com.
aslibra.com. 172800 in NS ns2.aslibra.com.
;; Received bytes from 192.31.80.30#53 (d.gtld-servers.net) in 252 ms

;; Connection timed out; No servers could be reached

At present I do not know that some of the domain name to provide a number of NS records what is the use, may be more backup, or for large demand-based.
For example, to provide a lot of domain Services, that provide NS1-NS6 you pick two, but the server architecture is six, if you and the superior service provider to apply for multiple, that can be filled in, to prevent the domain name resolution service crashes is invalid, may be helpful for the pressure distribution of the query.


Original content such as reproduced please specify: from the right of the study
Address: http://www.aslibra.com/blog/post/dig_dns_ns_record.php

Dig Understanding DNS Master Preparation-Aquan's Den