I'm not sure about the dynamic dns stuffin LMCE, but dynamic DNS works fine. You need to know what you are doing to forward ports from your modem/router and use a static IP on the external side of your core. The trick is grabbing the IP you show up as on the internet and using that to update your dynamic dns server. I actually setup my core with dynamic dns before learning about the dynamic dns stuff in LMCE. I'm also running dns on my core, using ddns only to point the nameserver for my domain to my dynamic IP. Using dyndns.com as my dynamic dns server, webhousens1.dnsdojo.com as the name server for my domain name, and inadyn as the script to update dyndns, here is my cron.daily job. It grabs my external IP from a dyndns.com website, checks to see if my external IP changed, updates my dns tables for things like mail and www, restarts my dns server, and updates my IP on dyndns:
#!/bin/sh
# Update dyndns if IP changes
wget
http://checkip.dyndns.com/ -O /tmp/realip
NEWIP=`awk -F: '{print $2}' /tmp/realip | awk -F\< '{print $1}'| sed s/' '//g`
OLDIP=`cat /tmp/oldip`
if [[ "$NEWIP" != "$OLDIP" ]]
then
echo $NEWIP > /tmp/oldip
sed s/NEWIPHERE/$NEWIP/g /etc/bind/db.webhouse.cc.blank > /etc/bind/db.webhouse.cc
/etc/init.d/bind9 reload
inadyn -u **MYLOGIN** -p **MYPASSWORD** --dyndns_system
dyndns@dyndns.org -a webhousens1.dnsdojo.com --iterations 1
fi
Hopefully this is easier and is more automated within LMCE, but as I said I set this up before realizing LMCE had this as an option.