After we have installed BIND as a master DNS server (NS1) (as explained in my recent post), we can now try to set up a secondary DNS server (NS2) with BIND on Cent OS.NS2 acts as a backup if there are problems with NS1.
Zone files don’t need to be created since they should be replicated from the master.This way, when making changes in some zone on the master, the slave gets notified and takes over the changes almost instantly without the need to do any configuration on the slave’s side.The example will be done with Cent OS 7 but the syntax of the commands should be equal for almost all Linux and Unix variants since Bind is quite universal. The IP of the machine which will be the master is 192.168.202.101.Note: There are some issues with this Howto, too numerable to fix quickly, and it requires bringing up to standard. in all other places, the document uses the machine name example ns.I'm mentioning this to help anyone to avoid the unnecessary time trying to resolve their DNS, owing the the inconsistencies in this document, particularly if you're new to DNS configuration. Here it changes to box (I believe the author was simply trying to show that additional computers would be listed, but failed to use a different address for box.In this way, DNS alleviates the need to remember IP addresses. Ubuntu ships with BIND (Berkley Internet Naming Daemon), the most widely deployed DNS server.In this configuration BIND9 will find the answer to name queries and remember the answer for the next query. By caching DNS queries, you will reduce bandwidth and (more importantly) latency.[[email protected] ~]# nslookup Server: 192.168.0.2 Address: 192.168.0.2#53 Name: Address: 192.168.0.1 Now if there's any problem with NS1 you can rest calm because NS2 acts as a backup. I created another slave DNS & here's the error I've got, I followed the intructions from 1 to 4. I modified the example file to give box an address of 192.168.1.21).Domain Name Service (DNS) is an Internet service that maps IP addresses and fully qualified domain names (FQDN) to one another.