Re: Caching DNS

> My application on an AWS server has been successfully sending emails using BLAT for a long time.
>
> Each of my users has a different email server (whatever they use for themselves separately from my application is what they use for my application).
>
> Just one of my many users occasionally runs into an error. Their email server's tech support has asked me if I can have my program start using a "caching DNS."
>
> Here's where I am naive. I don't know what this means, I don't know if I'm already using a caching DNS, and I don't know how to implement this.
>
> Can you advise me?
>
> Thank you... Art Lieberman


DNS stands for Domain Name System, and the job of a DNS server is to translate textual names for computers into IP addresses that can be used for all Internet traffic.  Internet Protocol (IP) is based entirely on numeric addresses assigned to every computing device connected to the Internet.  To make life easier for us humans, computer were given names, and a system was developed whereby these names could be translated into IP addresses.

Normally, a person’s Internet Service Provider is responsible for identifying one or more DNS servers that can be used to provide this translation service.  Company I.T. departments tend to provide a server for just this purpose, so they can limit the company network’s exposure to the outside world, and to block some sites deemed inappropriate for the company business.

As I understand it, your _application_ is not responsible for running and maintaining a DNS server.  My guess is that your client’s I.T. department would prefer that your program be configured to use Amazon’s DNS servers rather than the client’s DNS servers.  I don’t fully understand the reasoning for this.  Is the client running your application directly on their computer, and thus running Blat behind the scenes on their computer, or is this all taking place directly on Amazon’s computers through a web browser interface?  If your application is being interfaced through a web browser while being executed on Amazon computers, then the DNS queries will be handled by Amazon, not by your client’s I.T. department.  If your application is being hosted by Amazon, but run directly on the client’s PC, then that client’s I.T. department is out of their collective minds.

Chip