Solved

Public MX Records and Priority?

Posted on 2013-05-27
6
369 Views
Last Modified: 2013-06-19
Can you explain a public MX record and oriority?  If an MX record is attached to a public IP and friendly name how does the priority work?  Is a priority 5 higher than a priority 10?
0
Comment
Question by:iNetSystem
[X]
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
6 Comments
 
LVL 23

Expert Comment

by:Stelian Stan
ID: 39199524
The lower the number is the higher the priority. Like you said 5 is higher then 10.
0
 
LVL 4

Accepted Solution

by:
iammorrison earned 500 total points
ID: 39199528
A Mail Exchange (MX) record is a DNS object that is used to resolve email domains for SMTP. Even if DNS records exist for domain yourcompany.com ( if they have a website for example) if this domain wants to receive email, then it must also have a valid MX record pointing mail traffic to authorized mail server(s). Priority is given to the MX record with the LOWEST numbers first. To use your example, a record with a priority of 5 takes precedent over a record with priority 10.
0
 
LVL 4

Expert Comment

by:EddyvanOpdorp
ID: 39199556
Correct, how lower the number, how higher the priority.
If you have 2 record with the same priority it is random. This is called round robin.
0
Independent Software Vendors: We Want Your Opinion

We value your feedback.

Take our survey and automatically be enter to win anyone of the following:
Yeti Cooler, Amazon eGift Card, and Movie eGift Card!

 
LVL 43

Expert Comment

by:Amit
ID: 39199589
0
 
LVL 63

Expert Comment

by:Simon Butler (Sembee)
ID: 39199971
Of course everything about priority is theoritical.
In practise you will have email go to all hosts in the MX record, and if you have one with a higher cost then it will get more spam, as spammers target them.

I work on the basis that the priority means nothing, I don't use it with any of my clients. If they have multiple servers able to receive email then they all get the same cost - 10.
I don't believe that there is any round robin in MX records.

Simon.
0
 
LVL 46

Expert Comment

by:Craig Beck
ID: 39202633
In my experience the priority is not theoretical at all.

I have a MX record pointing to my primary SMTP server which is authoritative for my domain, but I also have a MX record pointing at a fallback SMTP server which isn't authoritative for my domain - it just acts as a relay so that if my SMTP server becomes unavailable it will store-and-forward.

Some of my clients have geographically distributed mail servers which manage the same domain.  The priority is the same on all MX records and mail delivery is totally random (as implied by round-robin DNS resolution).  If the SMTP server with the lowest priority is unavailable, the next SMTP server with the same priority isn't used though - the one with the next preferred priority is used.
0

Featured Post

Free Tool: ZipGrep

ZipGrep is a utility that can list and search zip (.war, .ear, .jar, etc) archives for text patterns, without the need to extract the archive's contents.

One of a set of tools we're offering as a way to say thank you for being a part of the community.

Question has a verified solution.

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

How to set-up an On Demand, IPSec, Site to SIte, VPN from a Draytek Vigor Router to a Cyberoam UTM Appliance. A concise guide to the settings required on both devices
How to resolve IMCEAEX NDRs in Exchange or Exchange Online related to invalid X500 addresses.
In this video we show how to create an email address policy in Exchange 2013. We show this process by using the Exchange Admin Center. Log into Exchange Admin Center.:  First we need to log into the Exchange Admin Center. Navigate to the Mail Flow…
In this Micro Video tutorial you will learn the basics about Database Availability Groups and How to configure one using a live Exchange Server Environment. The video tutorial explains the basics of the Exchange server Database Availability grou…

749 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