DH and random

Hi. When i've configured my freeradius i've seen 2 metods to create files DH and random: first: DH: openssl dhparam -check -text -5 512 -out dh Random: dd if=/dev/urandom of=random count=2 second: DH: date >/etc/1x/DH Random date > /etc/1x/random And I wondering what is different in theory and practice? my freeradius is acting, but i wanna understand for what i need this two file and is it never mind when i use instead of first, second method. THX for answers