[CentOS] Some relevant information

Hello everyone:

* DNS does not have a "refresh rate".  In DNS, the person running the
domain determines what the "refresh rate" (it's called TTL in DNS) for
their records is; for example, Google has a TTL of "once per hour" and
my domains (maradns.org, etc.) have a TTL of one day.

* As mentioned before, Scientific Linux 6.0 is out.  What hasn't been
mentioned here is that while SL 5.6 hasn't come out, 5.6 security
updates are being backported to SL 5.5.  Ditto with SL 4 (no 4.9 but
security patches look current)

Take care everyone,

- Sam