The following are the minimum required release levels for Red Hat Enterprise Linux AS 2.1 and Red Hat Enterprise Linux AS 3.0.
For Red Hat Enterprise Linux AS 2.1:
kernel version - 2.4.18-e.12 SMP
glibc - 2.2.4-29 or later
For Red Hat Enterprise Linux AS 3.0:
kernel version - 2.4.21-20
glibc - 2.3.2 release 95.x