Mongodb not listening on all interface
If you have firewall running, allow connections on port 27017, MongoDB default port.

Not sure which RHEL version you are running so below commands might change. 

1. Any connections can connect to MongoDB on port 27017

iptables -A INPUT -p tcp --dport 27017 -j ACCEPT


2. Only certain IP can connect to MongoDB on port 27017

iptables -A INPUT -s &lt;ip-address&gt; -p tcp --destination-port 27017 -m state --state NEW,ESTABLISHED -j ACCEPT
iptables -A OUTPUT -d &lt;ip-address&gt; -p tcp --source-port 27017 -m state --state ESTABLISHED -j ACCEPT


For Eg:

    iptables -A INPUT -s 192.168.6.100 -p tcp --destination-port 27017 -m state --state NEW,ESTABLISHED -j ACCEPT
    iptables -A OUTPUT -d 192.168.6.101 -p tcp --source-port 27017 -m state --state ESTABLISHED -j ACCEPT


Also i personally believe commenting bind option is not a good idea.

Instead you can use below in /etc/Mongod.conf :

# Listen to local and LAN interfaces.
bind_ip = 127.0.0.1,x.x.x.x, x.x.x.x


and then 

service mongod restart