Disabled clusters are unavailable

As of LoadMaster firmware version 7.2.53, a new check box named Disabled clusters are unavailable has been introduced. This option is disabled by default. When it is enabled, requests to the cluster are dropped if a GEO cluster is disabled. The cluster name on the Global Balancing > Manage FQDNs page of the User Interface (UI) will also be displayed in red text.

Glue Record IP

In LoadMaster firmware version 7.2.52, a new text box was introduced called Glue Record IP which allows you to set the IP address of the name server to return in additional records in a DNS response. Both IPv4 and IPv6 addresses are supported.

Glue records appear in query results if the following conditions are met:

  • A Zone has been configured

  • At least one Name Server has been configured and it belongs to the zone

  • The FQDN being queried is part of that Zone

For each name server that belongs to the zone, its glue record is returned.

Query failures occur when a glue record is to be returned, but it is not present on the system.

You can currently add glue records to the LoadMaster in the following ways:

  • In Global Balancing > Miscellaneous Params in the Glue Record IP field you can add a single glue record IP address and it will always correspond to the first name server configured in the Name Server field. The Glue Record IP field defaults to 0.0.0.0 if it is not set. The first Name Server is always guaranteed to have a glue record (0.0.0.0 if not set).

  • If more than one name server is configured that require glue records, a workaround is to add the name server (or servers) as an FQDN in Manage FQDNs and ensure that it has at least one IP address configured. This FQDN then acts as a glue record from BIND's point of view.

Note: If you change the configuration to a scenario where a SERVFAIL occurs due to the lack of a glue record, the issue may not manifest itself until GEO is restarted because BIND appears to be able to mask the issue by caching previous glue records.

TTL

The Time To Live (TTL) value dictates how long the reply from the GEO LoadMaster can be cached by other DNS servers or client devices. This value should be as practically low as possible. The default value for this field is 10. The time interval is defined in seconds.

TXT Record

In LoadMaster firmware version 7.2.52, support for the TXT (Text) record type was added to the GEO functionality. A TXT (text) record is essentially unformatted data that can be used for almost any purpose, but typically contain information to be consumed by clients to classify a domain in some way, provide details about a domain, or specify resources available within a domain.

The configured record is returned for a TXT request on any Fully Qualified Domain Name (FQDN).

A maximum of 127 characters can be entered as the global TXT record.

The following are not currently supported:

  • Multiple strings within the record: Some DNS providers allow you to put multiple strings in one entry using quotes, for example, "string 1" "string 2" "string 3". Progress Kemp does not currently allow this , so you can only have "string 1".

  • Non-ASCII characters.

EDNS Client Subnet (ECS)

In LoadMaster firmware version 7.2.57, a checkbox named EDNS Client Subnet (ECS) was introduced. ECS is an option in the Extension Mechanisms for DNS that allows a recursive DNS resolver to specify the subnetwork when making a DNS query on behalf of the host or client.

By default, the EDNS Client Subnet (ECS) checkbox is enabled on new installations but if you are upgrading a LoadMaster that previously used GEO functionality then the option is disabled. When enabled, the ECS field (if included in the request) is used to determine the client location. When disabled, this field is ignored.

Note: It is possible that a client that has EDNS enabled may be sending requests through recursive DNS servers that are not enabled for EDNS. That means the client subnet will be dropped from the UDP packet that is received by the LoadMaster. If the EDNS client subnet information is removed it will not be available for the LoadMaster to act on.