Rsync

<codeprism lang=bash>
# keep two folders sync, SRC needs '/' tailing
rsync -avzP --delete SRC DEST 
</codeprism>

nslookup

<codeprism lang=bash>
# How to specify a DNS server in nslookup?
nslookup isc.org 8.8.8.8
</codeprism>