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Amazon Route 53
Developer Guide (API Version 2013-04-01)

Values for Weighted Resource Record Sets

When you create weighted resource record sets, you specify the following values:

Name

Enter the name of the domain or subdomain for which you're creating the resource record set. The default value is the name of the hosted zone. If you're creating a resource record set that has the same name as the hosted zone, don't enter a value (for example, an @ symbol) in the Name field.

For information about how to specify characters other than a-z, 0-9, and - (hyphen) and how to specify internationalized domain names, see DNS Domain Name Format.

Enter the same name for all of the resource record sets in the group of weighted resource record sets.

You can use an asterisk (*) character in the name. DNS treats the * character either as a wildcard or as the * character (ASCII 42), depending on where it appears in the name. For more information, see Using an Asterisk (*) in the Names of Hosted Zones and Resource Record Sets.

Type

The DNS record type. For more information, see Supported DNS Resource Record Types.

Select the same value for all of the resource record sets in the group of weighted resource record sets.

Alias

Select No.

TTL (Time to Live)

The amount of time, in seconds, that you want DNS recursive resolvers to cache information about this resource record set. If you specify a longer value (for example, 172800 seconds, or two days), you pay less for Amazon Route 53 service because recursive resolvers send requests to Amazon Route 53 less often. However, it takes longer for changes to the resource record set (for example, a new IP address) to take effect because recursive resolvers use the values in their cache for longer periods instead of asking Amazon Route 53 for the latest information.

If you're associating this resource record set with a health check, we recommend that you specify a TTL of 60 seconds or less so clients respond quickly to changes in health status.

You must specify the same value for TTL for all of the resource record sets in this group of weighted resource record sets.

If a group of weighted resource record sets includes one or more weighted alias resource record sets for which the alias target is an ELB load balancer, we recommend that you specify a TTL of 60 seconds for all of the non-alias weighted resource record sets that have the same name and type. Values other than 60 seconds (the TTL for load balancers) will change the effect of the values that you specify for Weight.

Value

Enter a value that is appropriate for the value of Type. For all types except CNAME, you can enter more than one value. Enter each value on a separate line.

A — IPv4 address

An IP address in IPv4 format, for example, 192.0.2.235.

AAAA — IPv6 address

An IP address in IPv6 format, for example, 2001:0db8:85a3:0:0:8a2e:0370:7334.

CNAME — Canonical name

The fully qualified domain name (for example, www.example.com) that you want Amazon Route 53 to return in response to DNS queries for this resource record set. A trailing dot is optional; Amazon Route 53 assumes that the domain name is fully qualified. This means that Amazon Route 53 treats www.example.com (without a trailing dot) and www.example.com. (with a trailing dot) as identical.

MX — Mail exchange

A priority and a domain name that specifies a mail server, for example, 10 mailserver.example.com.

NAPTR — Name Authority Pointer

Six space-separated settings that are used by Dynamic Delegation Discovery System (DDDS) applications to convert one value to another or to replace one value with another. For more information, see NAPTR Format.

PTR — Pointer

The domain name that you want Amazon Route 53 to return.

SPF — Sender Policy Framework

An SPF record enclosed in quotation marks, for example, "v=spf1 ip4:192.168.0.1/16-all". SPF records are not recommended. For more information, see Supported DNS Resource Record Types.

SRV — Service locator

An SRV record. For information about SRV record format, refer to the applicable documentation. The format of an SRV record is:

[priority] [weight] [port] [server host name]

For example:

1 10 5269 xmpp-server.example.com.

TXT — Text

A text record. Enclose text in quotation marks, for example, "Sample Text Entry".

Routing Policy

Select Weighted.

Weight

A value that determines the proportion of DNS queries that Amazon Route 53 responds to using the current resource record set. Amazon Route 53 calculates the sum of the weights for the resource record sets that have the same combination of DNS name and type. Amazon Route 53 then responds to queries based on the ratio of a resource's weight to the total.

You can't create non-weighted resource record sets that have the same values for Name and Type as weighted resource record sets.

Enter an integer between 0 and 255. To disable routing to a resource, set Weight to 0. If you set Weight to 0 for all of the resource record sets in the group, traffic is routed to all resources with equal probability. This ensures that you don't accidentally disable routing for a group of weighted resource record sets.

The effect of setting Weight to 0 is different when you associate health checks with weighted resource record sets. For more information, see Configuring Active-Active or Active-Passive Failover by Using Amazon Route 53 Weighted and Weighted Alias Resource Record Sets.

Set ID

Enter a value that uniquely identifies this resource record set in the group of weighted resource record sets.

Associate with Health Check/Health Check to Associate

Select Yes if you want Amazon Route 53 to check the health of a specified endpoint and to respond to DNS queries using this resource record set only when the endpoint is healthy. Then select the health check that you want Amazon Route 53 to perform for this resource record set.

Amazon Route 53 doesn't check the health of the endpoint specified in the resource record set, for example, the endpoint specified by the IP address in the Value field. When you select a health check for a resource record set, Amazon Route 53 checks the health of the endpoint that you specified in the health check. For information about how Amazon Route 53 determines whether an endpoint is healthy, see How Amazon Route 53 Determines Whether an Endpoint Is Healthy.

Associating a health check with a resource record set is useful only when Amazon Route 53 is choosing between two or more resource record sets to respond to a DNS query, and you want Amazon Route 53 to base the choice in part on the status of a health check. Use health checks only in the following configurations:

  • You're checking the health of the resource record sets in a weighted, latency, geolocation, or failover resource record set, and you specify health check IDs for all of the resource record sets. If the health check for a resource record set specifies an endpoint that is not healthy, Amazon Route 53 stops responding to queries using the value for that resource record set.

  • You select Yes for Evaluate Target Health for the resource record sets in an alias, weighted alias, latency alias, geolocation alias, or failover alias resource record set, and you specify health checks for all of the resource record sets that are referenced by the alias resource record sets.

For geolocation resource record sets, if an endpoint is unhealthy, Amazon Route 53 looks for a resource record set for the larger, associated geographic region. For example, suppose you have resource record sets for a state in the United States, for the United States, for North America, and for all locations (Location is Default). If the endpoint for the state resource record set is unhealthy, Amazon Route 53 checks the resource record sets for the United States, for North America, and for all locations, in that order, until it finds a resource record set for which the endpoint is healthy.

If your health checks specify the endpoint only by domain name, we recommend that you create a separate health check for each endpoint. For example, create a health check for each HTTP server that is serving content for www.example.com. For the value of Domain Name, specify the domain name of the server (such as us-east-2-www.example.com), not the name of the resource record sets (example.com).

Important

In this configuration, if you create a health check for which the value of Domain Name matches the name of the resource record sets and then associate the health check with those resource record sets, health check results will be unpredictable.

For more information about checking the health of endpoints, see Creating Amazon Route 53 Health Checks and Configuring DNS Failover.