SmtpUseTcpDns Metabase Property (IIS 6.0)
The SmtpUseTcpDns property specifies if SMTP uses TCP for DNS. The value can be 0 (IE UDP only), 1 (TCP only), 2 (try UDP and then TCP), or others.
The metabase represents unlimited as the DWORD value of 4294967295 (0xFFFFFFFF); however, VBScript represents unlimited in hexadecimal format as &HFFFFFFFF. Previous versions of IIS represented unlimited as -1.
You can configure this property at the following locations in the IIS metabase.
For general code examples, see Code Examples to Configure Metabase Properties.