Introduction:

Wildcat! DNS (wcDNS) is a built-in DNS (Domain Name Server) client/resolver with local caching capabilities for the following modules:

• Wildcat! SMTP server (wcSMTP),
• Wildcat! Sender Authentication Protocol (wcSAP),
• Wildcat! DomainKeys Identified Mail (wcDKIM), and
• wcBASIC apps using the new wcDNS.wch resolver query functions.

wcDNS provides a tremendous boost in performance and query consistency between the wcSMTP, WCSAP and WCDKIM modules because they perform many DNS-based protocol lookup queries for mail transaction. For example, for a given incoming SMTP session, it is typical for the following DNS-application lookups to be done:/p>

 - PTR lookup to find the host name of the IP address (rDNS)
 - RBL lookup to see if the IP is blacklisted
 - SPF lookup to see if the IP is authorized
 - DKIM lookup to verify the DKIM signature of a message
 - ADSP lookup to see if the Author Domain has a DKIM 1st party policy
 - DMARC lookup to see if the Author Domain has a DKIM 1rd party policy
 - ATPS lookup to see if the Author Domain has a DKIM 3rd party policy

wcDNS optimization is performed using a local caching of the queries. The queries are stored in the "wcDNS\" subfolder.

The utility wcDNSCache is provided to view, search and pack/prune the DNS caching. It is ok to manually, delete the files in the folder or the folder itself. wcDNS will recreate the "wcDNS\" cache folder.

Normally, you don't need to worry about the wcDNS cache folder building up, however, it is recommended that a regular scheduled maintaince task is run to prune/pack the wcDNS cache. See the packing example.