check dns server for ipv6

netstat -an | grep ':53'

ref: http://www.linuxforums.org/forum/networking/30561-ipv6-bind-dns-server-problem.html

uneble to query whois on centos

[root@local ~]# whois apis17.info

[Querying whois.afilias.info]

[Unable to connect to remote host]

it is firewall blocking your query.

open outgoing port 43 and all done.. :)

update: whois query for IPV6 failed . then you should use debian or disable firewall temporarily (for centos)

Mailer Edition: Split DNS

http://wiki.zimbra.com/index.php?title=Split_dns

now trying this. still on my problem sending email outside world.

Update:

Trying this

http://webmail.tm.net.my/info/smtp-proxy.html#Sendmail

Latest:

http://doxfer.webmin.com/Webmin/SendmailConfiguration#Configuring_domain_routing