Could we configure DNS to use TCP ?

Posted on 2009-05-06
Last Modified: 2012-06-27
I feel by default DNS uses UDP protocol on port 53. Could we configure it to let it use the TCP as well ? /etc/services shows it support both TCP and UDP.
bash-3.00# grep 53 /etc/services 
domain          53/udp
domain          53/tcp

Open in new window

Question by:beer9
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
LVL 48

Expert Comment

ID: 24312665
Depends what DNS server you are running.

Author Comment

ID: 24314160
What if I am using BIND, does is support both TCP and UDP by default? Thanks!
LVL 62

Expert Comment

ID: 24314213
DNS over TCP is almost never used.
Any server out there supports DNS over TCP but no clients use that by default.
Since it is that rarely used I suspect more problems in there.
What does it mean to be "Always On"?

Is your cloud always on? With an Always On cloud you won't have to worry about downtime for maintenance or software application code updates, ensuring that your bottom line isn't affected.


Accepted Solution

jarrell earned 250 total points
ID: 24315868
Generally TCP uses UDP for speed, but if the answer doesn't fit into a single udp packet, it'll switch to using TCP.  Which I've seen cause problems with some clients; we broke some software when our SPF record (which is in a TXT on the domain names RR) got too big, and we were doing TCP all of a sudden.
LVL 62

Expert Comment

ID: 24318808
It depends on client. Some servers do send chain of UDP packets with huge record...

Author Closing Comment

ID: 31578360
Thank you :-)

Featured Post

Optimize your web performance

What's in the eBook?
- Full list of reasons for poor performance
- Ultimate measures to speed things up
- Primary web monitoring types
- KPIs you should be monitoring in order to increase your ROI

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

When you do backups in the Solaris Operating System, the file system must be inactive. Otherwise, the output may be inconsistent. A file system is inactive when it's unmounted or it's write-locked by the operating system. Although the fssnap utility…
In tuning file systems on the Solaris Operating System, changing some parameters of a file system usually destroys the data on it. For instance, changing the cache segment block size in the volume of a T3 requires that you delete the existing volu…
Learn several ways to interact with files and get file information from the bash shell. ls lists the contents of a directory: Using the -a flag displays hidden files: Using the -l flag formats the output in a long list: The file command gives us mor…
Learn how to navigate the file tree with the shell. Use pwd to print the current working directory: Use ls to list a directory's contents: Use cd to change to a new directory: Use wildcards instead of typing out long directory names: Use ../ to move…

630 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question