Most of us might have come across instances where mails from our domain are marked as spam even though it is legitimate. This article describes few settings that can be implemented in order to decrease the chances of mails originating from your domain being marked as spam.

Spamming can be prevented to a great extend by using anti-spamming DNS records such as SPF, DomainKey and reverse DNS.

SPF :

Sender Policy Framework (SPF) records helps to prevent spoofing of mails by verifying the sender’s IP address. SPF record allows domain owners to specify IP address from which mails will originate, so that receivers verifying the SPF records can reject messages from unauthorized sources before receiving the body of the message.

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IPv4 and IPv6 are addressing schemes to direct traffic across the Internet. IPv6 is the next generation in the Internet Protocol. Currently, almost all of the Internet traffic is directed using IPv4 address. It provides 2^32 (4,294,967,296) possible addresses. However, the increase in demand has lead to a shortage in the IP addresses. A solution for this shortage is the IPv6 scheme, which provides upto 2^128 addresses. It will also improve performance of the network by providing features like built in support for virtual private network protocols, multicast groups etc.

Unfortunately, cPanel haven’t incorporated IPv6 support till their current release i.e, 11.32. As per cPanel sources, IPv6 support will be officially included in cPanel from 11.36. Currently, IPv6 support is available with Plesk control panel.

The IPv6 assignment to the server can be done manually. On a Red-Hat machine, you will have to enable IPv6 support by modifying the file “/etc/sysconfig/network“.

The next step is to edit the network interface file, say “/etc/sysconfig/network-scripts/ifcfg-eth1” and specify the IPv6 parameters.

Restarting the network service is required for this change to be in effect.
IPv6 virtual hosts cannot be added from cPanel. You will have to manually edit the Apache configuration file to add IPv6 addresses. Initially you will have add a “Listen” directive in the Apache configuration file, so that it listen to a particular IPv6 address or all IP6 addresses.

To bind to a specific IP address :

Listen [2001:db8::a00:20ff:fea7:ccea]:80

To bind to a all available IP addresses:

Listen [::]:80

Once this change is made, you can add virtual hosts with IPV6 IP addresses. This can be added in the same way as virtual hosts with IPv4 addresses. IPv6 addresses must be specified in square brackets. In the similar way, we can switch all services to be IPv6 compatible.
Since version 11.32, all daemons in cPanel supports IPv6. But the required modifications in GUI are not yet implemented. We will have to wait till the release of cPanel 11.36 to manage IPv6 from the cPanel/WHM interface. Until then IPv6 addresses and their settings have to be managed via the command line.

The above is a very rough outline of the IPV6 , if you have any questions, we would be happy to talk to you!

About the Author :

Dipin D works as a Software Engineer in Bobcares. He joined Bobcares in September 2010. He loves reading books and listening to music in his free time.

Blog edited by :

Appu Joseph Xavier works as a Software Engineer in Bobcares. He joined Bobcares in April 2012. He loves to watch movies in his free time.

Ok, now that we know what IPv6 IP address are all about in part I and II, lets take a look at what it would be like using them for sites hosted on your server.

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I know I said I’d talk about IPv6 DNS records in this post, but I realized that we’d have to cover a few basics first. So lets cover those first before moving on…

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A DNS cluster is a number of nameservers that share records. This allows you to physically separate your nameservers, so that in the event of, for instance, a power outage, you still have DNS functionality. This way, visitors can reach websites on your server more quickly after the web server comes back online.

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Well, if your already setup, then you wont have to worry too much. At the current rate, the general opinion is that new hosts will have to be assigned IPv6 addresses by 2012(if the world doesn’t end). So if those hosts wish to communicate with the other IPv4 servers, using the IPv4 network infrastructure, hosts will have to start understanding both IPv4 and IPv6. At least till the transition is complete. To make the transition as smooth as possible, various transition mechanisms have been put forward, of which RFC 4213(Basic Transition Mechanisms for IPv6 Hosts and Routers) will make an interesting read for any Webhost who plans to buy servers after 2012. More after the jump.

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Smbind is a PHP-based software tool for managing DNS zones for BIND via the web interface. This supports the per-user administration of zones, error checking, and a PEAR DB database backend.

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I’ve learned that there is nothing more peaceful than a sleeping child - Anonymous, Age 30

To an Internet Administrator, there is nothing more peaceful than a stable and optimized DNS server. The moment there is a wrong configuration, the server wakes up and starts crying, sites and email goes down. An important part of keeping DNS that way is properly setting up the SOA records.

What are DNS Records. DNS records or Zone files are used for mapping URLs to an IPs. Located on servers called the DNS servers, these records are typically the connection of your website with the outside world. Requests for your website are forwarded to your DNS servers and then get pointed to the WebServers that serve the website or to Email servers that handle the incoming email.

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What is an MX Record

MX stands for Mail Exchange Records. MX records are used in DNS records(or Zone files) to specify how email should be routed.

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