Host records

Host records are the individual hosts that together comprise a domain within the DNS system.

Clicking on an existing host record will immediately open up the editor for that host. You may create and/or edit more than one host at a time. The 3-dots icon at the far right of each host includes links to Edit (same as clicking on the host directly), Clone (creates a new host, but prepoulates it based on the cloned host), Make inactive/active, and Delete.

Make inactive/active deserves special mention. When inactive, a host is hidden from any DNS results. This is great when you think you can delete a host, but want an easy undo if something needs to be reverted. For bonus points, you can even add a note to the host as a reminder of when it’s safe to permanently delete. Another use is for staging an upcoming new record by creating it and immediately marking it inactive. Then, when it’s production time, simply mark it active. Inactive hosts are shown in italics.

Fields

Hostname

The hostname is any subdomain (or subdomains) being configured on this domain. For example, to create the record www.your-domain.com on the domain your-domain.com, the hostname would simply be www.

To create a record for your-domain.com without any subdomain, leave the hostname blank. When viewing a list of all hosts, this blank status is shown by @. The @ isn’t needed for queries–it just helps show that there is no hostname.

For nested subdomains, enter them all together. A hostname of x.y.z would result in the actual record x.y.x.your-domain.com.

Wildcard hostnames are supported for most types.

Type

The DNS reocrd type. See supported types below.

TTL

This is the Time-To-Live which is the maximum time this record is allowed to be cached before a remote client needs to requery the server. Long times reduce load on your nameserver, but also extend the time a client may be using out-of-date information before requerying. In contrast, short times ensure clients are using up-to-date values (especially important for A, AAAA, and ALIAS records that point to IPs that may change rapidly) but result in increased load on your nameservers.

“Default” indicates that the host record should inherit from the domain’s “Default TTL”. This makes it easy to bulk-change multiple host records all at once by changing just that default TTL.

To avoid prolonged outages caused by configuration errors, DNScaster has a maximum of 1 day.

Priority

The priority value for an MX or SRV host. 5 is higher priority than 10.

Data

The specific data for the selected DNS Type.

Boundary

The Geo boundary or IP boundary associated with an A, AAAA, or ALIAS host.

Notes

Notes are just for you and have a variety of uses. For example, many services require a random-named TXT record as a verifier–add a note to indicate the service the TXT is for. Or add “delete after {date}” when decommissioning a service or hostname. Or list the internal ticket number that authorized a given record or change. Basically, notes are for anything that you or your team need to know or remember in the future.

Supported types

A

Points to an IPv4 address.

AAAA

Points to an IPv6 address.

ALIAS

Aliases one name to another. May be used on the base domain too (ie: hostname is empty). Dynamically mapped to A and AAAA records by the DNScaster engine. See ALIAS records.

CAA

Limits what certificate authorities are allowed to issue TLS certs for this domain.

CNAME

Somewhat like an alias name. May only be used on a subdomain record (hostname may not be empty) and no other records with the same hostname are allowed. Target record may be any other type. If the target domain is to be used with A and/or AAAA queries, consider ALIAS instead.

GEO

Configures Geo-closest routing. Set both the closest count and target domain tree in Data.

MX

Configures Mail eXchangers (servers) for this domain. Set priority in the Priority field and the mail server name in Data.

NS

Delegates a subdomain to an external nameserver. No non-NS records for the same subdomain are allowed. (The domain’s own NS records are automatically managed—no need to add them.)

PTR

Usually used as part of reverse DNS. Remember that your hosting provider will have to delegate a reverse DNS domain to your DNScaster nameservers.

SRV

For apps and protocols that support SRV records, configures host servers along with weights and priorities. Set the priority in the Priority field and weight, port, and target server name all in Data.

TXT

A general purpose text record that has a variety of uses. Per RFC 7208, SPF records should use TXT (and not the obsolete SPF type).

Automatic host records

DNScaster automatically creates and manages the SOA record along with the NS records (plus A and AAAA records for any vanity names) for the domain itself.

The SOA’s TTLs comes from the domain’s Default TTL and the Hostmaster may be changed at Preferences -> NS Set Prefs -> Domains.

The NS record TTLs may be set at Preferences -> NS Set Prefs -> Nameservers -> “TTL for NS records”. We recommend 3 hours unless you are actively migrating out of DNScaster.

For any required A and AAAA records created for vanity names, those TTLs may be set at Preferences -> NS Set Prefs -> Nameservers -> “TTL for A & AAAA records”. Longer times will improve caching, at the slight risk of a longer service degredataion in the event of a nameserver failure. Shorter times improve recovery from a nameserver failure, but will result in higher query rates the rest of the time. We discourage anything lower than 15 minutes unless you are actively migrating out of DNScaster and are using vanity names.