reverse DNS problem

Hi,
I have setup DNS www.networkshastrihall.com, IP address "202-63-167-192". dig www.networkshastrihall.com works fine.

I have created mysql user as follows :
GRANT SELECT,INSERT,UPDATE,DELETE,CREATE,DROP ON bankaccount.* TO ads123@'www.networkshastrihall.com' IDENTIFIED BY 'xxxxx';
Query OK, 0 rows affected (0.00 sec)
mysql> FLUSH PRIVILEGES;
Query OK, 0 rows affected (0.00 sec)

I want to connect to mysql database as user ads123 as follows :

[root@allweb root]# mysql -h www.networkshastrihall.com -u ads123 -p bankaccount
Enter password:
ERROR 1130: Host '202-63-167-192.exatt.com' is not allowed to connect to this MySQL server.

It seems reverse DNS gives '202-63-167-192.exatt.com' instead 'www.networkshastrihall.com'

I am told it is due to reverse DNS problem. DNS is broken.
I am totally new to reverse DNS concept and I don't know why it is required.
Guide me why reverse DNS required and to solve problem.

Thanks

I checked follows :

[root@shastrihallweb root]# host 202.63.167.192
192.167.63.202.in-addr.arpa domain name pointer 202-63-167-192.exatt.com.

It should point to www.networkshastrihall.com.

Help appreciated.
Thanks

Just because you brought networkshastrihall.com doesn't imply the IP you point your domain to belong to you. If whatever IP you point your own domain to become your own property then everyone on earth can own a hundred of IPs.
When you don't own that IP, you can't control what name it points to. Over 99% of people misinterpreted reverse DNS and blindly believe that you point your domain to a particular IP, then that IP will point back to your domain automatically, that's never true. If you want reverse DNS to work, ask exatt.com to change their existing PTR record to your domain, but I don't think they'd do it even if you are willing to pay them $1000. If you really want reverse DNS to work, go for SpeakEasy.net.

I am trying to setup network having
1) Linux server running IPTABLES firewall, squid, dns server.
2) DMZ having apache, mysql and php, mail server.

User will use script from remote host to connect mysql as follows:

MYSQL_CONNECT("localhost", "abc", "abc" ) OR DIE("Unable to connect to database");
@mysql_select_db("abc") or die("Unable to select database");

where local host will be dmz.

Is it O.K. if I give all user give host as "localhost" in script?
Will it invilve any security problem?
If so what is generally done in this type of case.
Thanks for support.

Sorry, off topic.