About Request.UserHostName

Background

• I'm making asp.Net app that work on IIS 7.5/6.0.
• The app log client's host name and I use Request.UserHostName to know client's host name.

My Understanding about Request.UserHostName

1. Client request to my app.
2. My app get Request.UserHostName
3. .net ask host name to DNS server.
   maybe by IP?
4. DNS server response host name.

Question

• Is my understanding about Request.UserHostName right?
• How does it occur? if DNS server delay.
  Will my app wait DNS server's respnse?