homepage Welcome to WebmasterWorld Guest from 54.211.230.186
register, free tools, login, search, pro membership, help, library, announcements, recent posts, open posts,
Become a Pro Member
Home / Forums Index / Hardware and OS Related Technologies / Website Technology Issues
Forum Library, Charter, Moderators: phranque

Website Technology Issues Forum

    
Question About DNS and 2-Tier CNAME Records
scubby

5+ Year Member



 
Msg#: 3664247 posted 3:18 pm on Jun 1, 2008 (gmt 0)

Let's say I have the following configuration in my DNS records:

I have a CNAME record that is pointing www.domain1.com to www.domain2.com. However, in the DNS information for www.domain2.com, there is a CNAME record forwarding it to www.domain3.com. So www.domain1.com is actually pointing to www.domain3.com.

Is this possible? And if so, would this cause ANY slow down to the end user due to the 2 tier CNAME setup (2 DNS lookups instead of 1)? Or is all this stuff cached anyways? (Speed is paramount for this project)

 

Romeo

10+ Year Member



 
Msg#: 3664247 posted 4:09 pm on Jun 2, 2008 (gmt 0)

Hi Scubby,

just looking for the CNAMEs, it is actually 3 DNS lookups instead of 1 (there are 3 names to look up: 2x CNAMES and finally 1x A record).
However, before getting at this level to look up individual records, the user has to lookup the authoritative DNS servers for every domain first and then deal with 3 DNS servers.
So the overhead (if no rootserver lookup is needed) is 6 lookups instead of 2.

This stuff *may* eventually get partially cached at the user's end. I know about A records being cached. But I don't know about CNAMEs and NS. Perhaps different resolvers may have diferent policies -- don't know either.
And all that stuff has to be looked up at least once before it can eventually get cached on the user's end.

So, for performance reasons, defining the A record IP address inside the DNS of domain1.com would avoid overhead.

Kind regards,
R.

Global Options:
 top home search open messages active posts  
 

Home / Forums Index / Hardware and OS Related Technologies / Website Technology Issues
rss feed

All trademarks and copyrights held by respective owners. Member comments are owned by the poster.
Home ¦ Free Tools ¦ Terms of Service ¦ Privacy Policy ¦ Report Problem ¦ About ¦ Library ¦ Newsletter
WebmasterWorld is a Developer Shed Community owned by Jim Boykin.
© Webmaster World 1996-2014 all rights reserved