DNS Record Types Explained
This article extensively covers the different types of DNS records with examples for each.
A Record The majority of DNS records are “A” records. A records allow for you to point different sections of your domain to different IP addresses or servers. For example, this would be useful for having “www.domain.com” point to your web server’s IP address and “mail.domain.com” point to your mail server’s IP address. Each record includes a “Host Name” value and a corresponding IP Address. Record field: The record name for that A record. The host name will precede the “.domain.com”. For example, adding a host name of “www” would translate to “www.domain.com”. The “www” would point to the specified IP address in the A record. Address field: The IP address you wish for the A record to point to. For example, an A record name of “www” could point to “188.8.131.52″, while an A record name of “mail” could point to “184.108.40.206″. Examples A records: www, mail, ftp, webmail, www2, secure, store, dev
CNAME Record CNAME records point to domain names, as opposed to specific IP addresses. This is very useful in that you can point a CNAME record to a domain name, change the record value for that domain name, and the CNAME record will reflect the updated record value. This is most commonly used when dealing with several top level domain versions (.com, .net, .org, etc.) of the same domain name. For example, if you own “domain.com” and “domain.net”, instead of having to keep both domain name’s records in sync with each other so that they resolve to the same IP address, you can simply create CNAME records for “domain.net” to mimic the “domain.com” records. That way, when changing records for “domain.com”, it will automatically be reflected on “domain.net” as well.
Record field: The host name for that CNAME record. The host name will precede the “.domain.com”. For example, adding a CNAME record name of “www” would translate to “www.domain.com”. The “www” would point to the same IP address of the domain name value entered for the CNAME record.
Address field: The domain name you wish for the CNAME record to mimic. For example, a CNAME record of “www” could point to “dev.anotherdomain.com”. This allows “www.domain.com” to always point to “dev.anotherdomain.com” even when the IP address is changed or updated. Example CNAME record: Record: webmail Address: mail.hostedmail.com
MX Record An important part of the email delivery system is “MX” records. MX records essentially tell the world what server to send mail to for a particular domain name. Priority field: The priority preference for that MX record. MX records are processed in order starting with the one with the lowest priority value and working towards high priority records. In situations where you have multiple email servers, or backup email servers, set a lower priority value for your primary mail server and a higher priority value for your backup server.
Record field: You can specify a 3rd level mail domain here, but typically you will want to leave it as “@” to specify the record is for the root domain name.
Address field: The address of the target mail server. It is recommended to use a domain name value here as opposed to an IP address. Typically you would first create an “A” record of “mail” pointing to the IP address of your mail server, and specify “mail.domain.com” here as the address entry for the MX record. Example MX records: Priority: 10 Record: @ Address: mail.domain.com Priority: 20 Record: @ Address: mail2.domain.com
TXT Record Typically a TXT record is used to get information about a domain. They can be used to specify what email servers are allowed to send mail for your domain with what is known as a “Sender Policy Framework (SPF)” record – which is very useful in combating spammers from falsely marking spam emails as from your domain name. They can also be used to provide a public “DomainKey” to be used to further prove the identity of emails being sent from your mail server to prove to spam filters that your domain’s email is legitimate email.
Record field: The name of the TXT record. For example, to create an SPF record you would want to leave it as “@” to specify the record is for the root domain name. DomainKeys require a more detailed record name.
Address field: This is the value of the TXT record. Example TXT records: Record: @ Address: v=spf1 a mx -all Record: dkDomain._domainKey Address: p=MHwwDQYJKoZIhvcNAQEBBQADawAwaAJhANZYB0
DKIM: DKIM (DomainKeys Identified Mail) is an important authentication mechanism to help protect both email receivers and email senders from forged and phishing email. Forged email is a serious threat to all parties in an email exchange.