How does RHEL determine the FS type when you run mkfs?

In Solaris there was /etc/default/fs - I can not find any sort of configuration file or parameter which defines the default filesystem type to use (if none is specified).

On a more annoying note: my team (all ex-Solaris guys, including myself) generally run a mkfs without a -t ... and better yet, we would add 'ext4' to /etc/fstab for our newly created FS. It seems that RHEL will mount an ext2 filesystem using ext4 in the fstab.

[root@tmsapp01 ~]# file -sL /dev/mapper/ORAAPPVG-LV_U01
/dev/mapper/ORAAPPVG-LV_U01: Linux rev 1.0 ext2 filesystem data (mounted or unclean) (large files)
[root@tmsapp01 ~]# grep u01 /etc/fstab
/dev/mapper/ORAAPPVG-LV_U01 /u01 ext4 defaults 1 2

I think my issue is too wide-spread for this to be a bug.. but I have some homework now ;-)