Basic DNS records

Overview

This article outlines the various types of records that are set up for a domain and what they are for. You can find your Mail DNS records using the DNS tab on the Manage Websites page. See the Adding DNS article for more information.

See also: List of DNS record types on Wikipedia

A
This is the "Address" record (A record) to forward the hostname to an IPv4 address.
AAAA
This is the IPv6 address record. You can use this to forward the mapping of the hostname to an IPv6 address.
ALIAS
An ALIAS record is a virtual DNS record similar to a CNAME, but with the ability to add it to the root domain name (which is not possible with a CNAME). It can also be added to a subdomain record that already exists where a CNAME must be unique.
CAA
A Certification Authority Authorization (CAA) record is used to specify which certificate authorities (CA) are allowed to issue a certificate for a specific domain name.
CNAME
The “canonical name record” or CNAME record points one domain name to another domain name.
MX
Also known as "mail exchange" records, which show you the host record the domain is pointing to for mail hosting.
NAPTR
Name Authority Pointer (NAPTR) records are most often used for Internet telephony.
NS
Nameserver records delegate a domain or subdomain to a DNS server.
PTR
Also called a “pointer record”. This is used for the reverse mapping of an IP address to a hostname. DreamHost currently only supports reverse DNS records when a Unique IP is added to a domain.

Note: Please note that a Unique IP address cannot be used to resolve mail blocking issues on shared email hosting.

You can read more about Unique IPs here:
SPF
Sender Policy Framework (SPF) records specify what mail servers are permitted to send email from your domain.
SRV
"Service locator" records advertise a specific service that a server offers.
TXT
Txt records are free-form text strings. They can be used for things like Google verification records and DKIM signing for mail services. 

You can find further information regarding IP addresses and the two types that are used in the following article:

Additional details

Below are some additional details regarding different DNS records or terminology:

DNS A record lookup

When looking up an A record, you may get a CNAME record in response, for example:
[server]$ dig www.cloudflare.com
www.cloudflare.com. 260 IN CNAME
www.cloudflare.com.cdn.cloudflare.net.
www.cloudflare.com.cdn.cloudflare.net. 260 IN A 198.41.215.163
www.cloudflare.com.cdn.cloudflare.net. 260 IN A 198.41.214.163
  • You can look up the A record of that CNAME record. You will either be presented with yet another CNAME record or an A record.

Fully qualified domain name

A FQDN is a unique domain that can't be confused with another. For example, if your site was example.com, you may have several FQDNs.

  • www.example.com

View the following article for further details:

Zone file

A Zone file is a text record that contains the mapping of your domain and subdomains to their corresponding IP addresses. View the following article for further details:

DreamHost does not offer a service to export your domain's zone file. If you need a list of the domain's records, you must copy your DNS records from your panel.

SOA record

The Start of Authority record is the first resource record in a DNS Zone file. The SOA record specifies the following authoritative information about a specific domain:

  • Primary name server of where the SOA record was created.
  • Admin email of the zone file. (A period is used in place of the @ symbol).
  • The domain's serial number. This is the revision number of the zone file.
  • Timers:
    • Refresh time
    • Retry time
    • Expire time
    • Minimum TTL

Run the following command via SSH to look up an SOA record. This example looks up dreamhost.com:

[server]$ nslookup -type=soa dreamhost.com

      Server:    64.90.63.202
      Address:   64.90.63.202#53
	  
	  Non-authoritative answer:
	  dreamhost.com
	  origin = ns1.dreamhost.com
	  mail addr = hostmaster.dreamhost.com
	  serial = 2015091000
	  refresh = 14534
	  retry = 1800
	  expire = 1814400
	  minimum = 14400

See also

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