Getting more out of dig

This article discusses dig's more verbose output options, then answers some common questions about dig not discussed in the previous two articles in this series, Verifying DNS configurations and Using dig with external nameservers.

Verifying DNS configurations

This article explains use of the open source "dig" tool to verify your Slicehost DNS configuration as a follow-up to our DNS Administration Guide.

Using dig with external nameservers

This article explains how to use the open source tool "dig" to query records on an external DNS server. The previous article in this series, Verifying DNS configurations, covered manually checking new DNS configurations on Slicehost's DNS servers.

Email - setting a Sender Policy Framework (SPF) record

Spam. No one likes it. No one wants it. No one needs it. However, it is there and is likely to be there for the foreseeable future.

All we can do as responsible mail server administrators is to ensure we are not part of the problem by not running an open relay and locking down our services as much as possible.

One tool that can help our legitimate email not being classed as spam is to set a Sender Policy Framework (SPF) record in our domain's DNS zone.

Postfix - using Telnet to test postfix

So far, we have sent test emails using the command line.

However, there is no real feedback from these clients as to how our mail server responded - did it respond with the correct details? Note that it is possible to send/receive mail with details that are not 100% correct - leading to issues down the line.

Let's look at telnet to check the server responses to mail requests.

Postfix - MX records and receiving emails

So far, we have prepared the Slice, installed postfix and had a quick look at the postfix file.

From that solid base, we can send mail and we know it all works according to plan. Now we can move onto receiving emails. To do that, we need to create the correct MX records and open port 25 in our iptables firewall.

Email - preparing the Slice

Beginning a series of articles on many aspects of email (sending, receiving, configuring, etc), we need to start with the very basics by preparing the Slice.

This article looks at the hostname and reverse DNS (RDNS) settings on the Slice.

ebook - DNS administration

The SliceManager DNS panel allows for powerful management of your domains' DNS records with the easy to use interface.

Learn how to add DNS zones and configure individual A, CNAME and MX records along with much more.

Creating MX records for Google Apps

A common way of handling email for your domain is to use Google Apps.

However, there can be some confusion in setting up the Mail Exchange (MX) records. Let's go through the procedure now.

Create a Mail Exchange (MX) record

Most people use email with their domains. To use email, we need a Mail Exchange (MX) record so any domain email is sent to the right place (whether that is a mail server on the slice or an external mail provider).

Let's set that up now.

Creating a Reverse DNS record

When you enter a domain name into your browser, the DNS system will find the IP address of the server the domain is associated with.

A reverse DNS lookup does the opposite. It establishes what domain is associated with the IP address. This is a useful setting to configure for anyone but essential for those running a mail server for example.

Creating DNS records

Creating DNS records for your domain is easy to do within the Slicehost Management Panel.

In this article we will look at creating a DNS zone for your domain and adding basic A and NS records using the SliceManager interface.

Introduction to dig

Made DNS changes? Not sure if they are correct? Don't want to wait for the changes to propagate before discovering a small typo?

No problem. Using the common but often ignored command 'dig', we can query DNS servers for records, specify records and even specify which DNS server to query.