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TR7Enterprise Application Delivery & Security Platform
What is a DNS record in GTM; which record types are supported?
Short answer
In GTM, a DNS record (Records) defines the answer the DNS Service will give for a single name and type under a domain: Record Name, Record Type, TTL and one or more addresses. Its difference from a classic DNS record is that, in the HC column, each address is bound to Static, Disabled or a health scenario, and that the answer is produced to suit the current state according to the Balance Algorithm, Topological Selection and Fail-Safe Records settings. The Record Type list contains 35 types (supported types). The operating mode of the record (Record Behavior) is not selected in the record; it comes from the domain's Default Mode setting.
How Does It Work?
The answer of a record is formed in the following order (record resolution logic):
- Health filtering: An address whose HC value is Static can always be included in the answer, an address bound to a health scenario is included only while the scenario is active, and a Disabled address is never included.
- Operating mode: In Standalone, the healthy addresses in the single group become candidates; in Disaster Recovery, those of the Main DC or, under the switchover condition, those of the DR DC; in Datacenter, those of the selected data centers.
- Distribution: The candidates are turned into the answer with the Balance Algorithm and, if it is on, with the Topological Selection rules.
- Last resort: If no candidate remains, Fail-Safe Records are returned.
The evaluation is repeated as the health check, health scenario and data center information changes; the resulting status appears in the Status column of the Records list.
The Record in TR7
The record is defined in the Records tab of the DNS Service, for the domain selected in the toolbar.
| Field | What it determines |
|---|---|
| Record Name | The name under the domain; @ is the domain itself, * and *.x are wildcard names. It is locked in the editing form. |
| Record Type | The record type; in types such as MX, SRV, RP and SOA, the address is entered with sub-fields (type-specific fields). It is locked in the editing form. |
| TTL | How long the answer stays in the cache; the default is 3600 seconds (What does a record's TTL determine; how should it be chosen in GTM?). |
| Record Behavior | Standalone, Disaster Recovery or Datacenter; it comes from the domain and is locked. |
| Record / HC | The addresses per data center group and the health condition of each address. |
| Balance Algorithm, Topological Selection, Fail-Safe Records | Selection among the healthy addresses, selection by location, and the last-resort addresses. |
Supported types (35): A, AAAA, AFSDB, ALIAS, CAA, CDNSKEY, CDS, CERT, CNAME, DNAME, DNSKEY, DS, HINFO, KEY, LOC, MX, NAPTR, NS, NSEC, NSEC3, NSEC3PARAM, OPENPGPKEY, PTR, RP, RRSIG, SMIMEA, SOA, SPF, SRV, SSHFP, TKEY, TLSA, TSIG, TXT, URI.
Common Misconceptions
- "The name or type of a record can be corrected later." Record Name and Record Type are locked in the editing form; to change them, the record is deleted and added again.
- "A separate operating mode is selected for each record." The mode comes from the domain's Default Mode setting; when the domain's mode changes, its records also switch to the new mode (What is the difference between the Standalone, Disaster Recovery and Datacenter modes?).
- "A health check is bound directly to an address." A health scenario is selected in the HC column; the health checks are combined inside the scenario (How does a Health Check result affect the DNS answer?).
- "The SOA record is created manually." In every domain, a single SOA record is added automatically when the domain is created; if it is deleted, it is created again with the default content (SOA record).
How it is done in the documentation
