Thank you…this is very useful information; I thought TTL could only be 
specified on a per-zone basis, not per-host.

On Jun 25, 2021, at 11:10 AM, Richard T.A. Neal 
<rich...@richardneal.com<mailto:rich...@richardneal.com>> wrote:

Hi Bruce,

Here you're specifying a distinct TTL for those records which overrides the 
default TTL for this zone (which you will have set towards the top of the file 
with the rest of the defaults)

1m = 60 seconds:
https://web.mit.edu/rhel-doc/5/RHEL-5-manual/Deployment_Guide-en-US/s1-bind-zone.html

So you're essentially telling DNS clients that the value provided for 
mail.{your-fqdn} is only valid for 60 seconds. As you say, a cheap load 
balancing attempt!

Best,

Richard.

-----Original Message-----
From: bind-users <bind-users-boun...@lists.isc.org> On Behalf Of Bruce Johnson
Sent: 25 June 2021 6:56 pm
To: bind-users@lists.isc.org
Subject: Odd A record in our hosts zone file

I ran across these A records in one of our zone files:

;EXCHANGE STUFF
mail            1m      IN      A       xxx.xxx.xxx.52; dhbex1
mail            1m      IN      A       xxx.xxx.xxx.54; dhbex2

I can see that this is a cheap load-balancing for our exchange OWA servers, but 
what is the ‘1m’ notation? I haven’t been able to find that in my searching of 
the manual.

(We’re adding new servers and I need to make sure our DNS is properly set for 
them.)

--
Bruce Johnson
University of Arizona
College of Pharmacy
Information Technology Group

Institutions do not have opinions, merely customs

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--
Bruce Johnson
University of Arizona
College of Pharmacy
Information Technology Group

Institutions do not have opinions, merely customs

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