add paragraph on CH/IN name space overlap
add paragraph on CH/IN name space overlap

pecharmin/bind9,pecharmin/bind9,pecharmin/bind9,pecharmin/bind9,each/bind9-collab,each/bind9-collab,each/bind9-collab,each/bind9-collab,each/bind9-collab,pecharmin/bind9,pecharmin/bind9,each/bind9-collab