Secondary DNS
The previous tutorial described a DNS server on the same machine as the web server using a single IP address. That works just fine if all you are doing is hosting simple websites. In that case, a good argument can be made that if the web server goes down for some reason (along with the DNS server, most likely), that a secondary DNS server can’t help visitors get to your website because the web server is down anyway. And all of that is true.
Where it makes a difference is when you have clients who are counting on email that is handled by your server. So if you have a business that is hosting its email with you and your only DNS server is down, mail will be immediately returned to senders as a bad email domain. Obviously having email returned to customers would not be good for business. But if you had a secondary DNS server running someplace the sender’s email server will hold the email message until your email server comes back up, then try sending again.
So if your business reaches a point where you believe that a secondary DNS server is necessary, you need to consider a solution. If you only have a limited number of domains then you might consider a free service to host your secondary DNS. You might consider BuddyNS.com for that. It’s very good service, and you can host an unlimited number of DNS zones (domains) with them, but you will have to enter new domains manually.
If you are going to be running a hosting business where a lot of domains are likely to be created or deleted, particularly if you are going to have resellers who will be creating domains that you aren’t even aware of, then you need to find a more automated solution. To that end, I am going to provide an automated method of making the slave DNS server aware of new or deleted domains.
It’s important to understand that while BIND comes with the capability to automatically update zones, it does not have the capability to know when new zones are added in the master DNS server. The first part of this tutorial will be to take care of that by transferring a zone list to the slave server.
Where it makes a difference is when you have clients who are counting on email that is handled by your server. So if you have a business that is hosting its email with you and your only DNS server is down, mail will be immediately returned to senders as a bad email domain. Obviously having email returned to customers would not be good for business. But if you had a secondary DNS server running someplace the sender’s email server will hold the email message until your email server comes back up, then try sending again.
So if your business reaches a point where you believe that a secondary DNS server is necessary, you need to consider a solution. If you only have a limited number of domains then you might consider a free service to host your secondary DNS. You might consider BuddyNS.com for that. It’s very good service, and you can host an unlimited number of DNS zones (domains) with them, but you will have to enter new domains manually.
If you are going to be running a hosting business where a lot of domains are likely to be created or deleted, particularly if you are going to have resellers who will be creating domains that you aren’t even aware of, then you need to find a more automated solution. To that end, I am going to provide an automated method of making the slave DNS server aware of new or deleted domains.
It’s important to understand that while BIND comes with the capability to automatically update zones, it does not have the capability to know when new zones are added in the master DNS server. The first part of this tutorial will be to take care of that by transferring a zone list to the slave server.
No comments:
Post a Comment