The default can be changed inside the config file caCert.profile located
somewhere (/var/lib/rhpki-ca/conf  ???).
The line reads 2.default.param.range=720  which you can change and then
restart your CA.  
I used RedHat CA and not the dogtag version therefore the path and field
names may differ from what I quoted.
 
From: Julius Adewumi 
@GDC4S.com 
________________________________
From: pki-users-bounces(a)redhat.com [mailto:pki-users-bounces@redhat.com]
On Behalf Of Uzor Ide
Sent: Monday, January 11, 2010 5:07 PM
To: pki-users(a)redhat.com
Subject: [Pki-users] CA Validity
Hi All
Am new to the Dogtag Cert server. Am testing it out for my company. 
Please I need direction on how to change the number of years of validity
for the Security Domain Certificate Authority Certificate. 
After the installation and setup I found the CA Signing Certificate has
only 2 years validity. 
Even after trying to change it through the profile and re-running the
setup I still ended up with 720 days certificate.
Can anybody help and point me in the right the direction.
Thanks in advance for your help.
Ide