TDNSQuery Last Updated: 01/27/2007 |
Frequently Asked Questions for TDNSQuery:
Aborting a DNS query request
Francois Piette francois.piette@overbyte.be 08/07/2003 |
In my app I dynamically create a DNS Query component and send a DNS Query request. Under certain circumstances I need to cancel the request and delete the dynamically created component. Is there a way to cancel the DNS Query request while it is in process and avoid the Request Done event from firing
The DNS component work with UDP, that is a connectionless protocol. It means that if you have one component sending a request to the DNS server, destroy the component, create a new one, this one will receive the UDP reply from the server. There is nothing you can do to prevent receiving it. But there is a solution: each request has is own ID (protected property FIDCount). If you make it public, you'll be able to change the value so that it remains unique across component destruction/construction. Then when a reply is received from a previous component request, it would be rejected because the ID is not the right one. |
Is it possible to have non blocking, event driven reverse DNS?
Francois PIETTE francois.piette@overbyte.be 05/01/2002 |
Yes, using TDnsQuery component which bypass winsock DNS (reverse) lookup and directly talk to any DNS.
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Query from email address
Francois PIETTE francois.piette@overbyte.be 06/05/2001 |
> how can I use TDnsQuery if I only have email addresses ?
From the EMail address, you extract the domain name. Using that domainname, you use TDnsQuery to query MX record from any DNS server (preferablyyour ISP DNS server). That MX record will give you a list of mail server forthe domain (if any exists) with a priority level. Then you can connect to any of those servers and try to send the mail. |