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Manual Chapter : Configuring a RCODE to Return a Response

Applies To:

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BIG-IP LTM

  • 17.0.0, 16.1.2, 16.1.1, 16.1.0, 16.0.1, 16.0.0

BIG-IP DNS

  • 17.0.0, 16.1.2, 16.1.1, 16.1.0, 16.0.1, 16.0.0
Manual Chapter

Configuring a RCODE to Return a Response

Overview: Configuring an RCODE to return a response to the client when load balancing fails

You can use BIG-IP DNS to configure a return code (RCODE) to return a response to the client when load balancing fails. Only when load balancing fails and the RCODE configuration is enabled, will an RCODE response be returned.
There are two types of load balancing failures where an RCODE response will be returned:
  • When using all the Primary and Alternate methods for wide IP pools.
  • When using a Return to DNS load balancing method.

Creating a pool with an applicable pool type

Ensure that at least one virtual server or wide IP exists in the configuration before you start to create a load balancing pool.
Create a pool in order to configure the BIG-IP system to load balance global traffic.

Creating a pool with pool type A or AAAA

Create an A or AAAA pool type in order to configure the BIG-IP system to load balance global traffic.
  1. On the Main tab, click
    DNS
    GSLB
    Pools
    .
    The Pool List screen opens.
  2. Click
    Create
    .
    The New Pool screen opens.
  3. In the General Properties area, in the
    Name
     field, type a name for the pool.
    Names must begin with a letter, and can contain only letters, numbers, and the underscore (_) character.
    The pool name is limited to 63 characters.
  4. From the
    Type
     list, depending on the type of the system (IPv4 or IPv6), select either an
    A
     or
    AAAA
     pool type.
  5. In the Configuration area, for the
    Health Monitors
     setting, in the
    Available
     list, select a monitor type, and move the monitor to the
    Selected
     list.
    Hold the Shift or Ctrl key to select more than one monitor at a time.
  6. In the Members area, for the
    Load Balancing Method
     setting, from the
    Preferred List
    , select
    Round Robin
    .
    When deploying this implementation in a lab environment, to determine whether the BIG-IP system returns the DNS response that you expect, try selecting the
    Global Availability
     method and disabling the first pool member in the list.
  7. From the
    Alternate
     and
    Fallback
     lists, select a static load balancing method, based on your network environment. Ensure that you select a load balancing method that does not take current server performance or connection load into account.
  8. In the Members area, for the
    Member List
     setting, add virtual servers as members of this load balancing pool.
    The system evaluates the virtual servers (pool members) in the order in which they are listed. A virtual server can belong to more than one pool.
    1. Select a virtual server from the
      Virtual Server
       list.
    2. Click
      Add
      .
  9. Click
    Finished
    .

Creating a pool with pool type NAPTR

Create an NAPTR pool type in order to configure the BIG-IP system to load balance global traffic.
  1. On the Main tab, click
    DNS
    GSLB
    Pools
    .
    The Pool List screen opens.
  2. Click
    Create
    .
    The New Pool screen opens.
  3. In the General Properties area, in the
    Name
     field, type a name for the pool.
    Names must begin with a letter, and can contain only letters, numbers, and the underscore (_) character.
    The pool name is limited to 63 characters.
  4. From the
    Type
     list, select the
    NAPTR
     type.
  5. In the Members area, for the
    Load Balancing Method
     setting, from the
    Preferred List
    , select
    Round Robin
    .
    When deploying this implementation in a lab environment, to determine whether the BIG-IP system returns the DNS response that you expect, try selecting the
    Global Availability
     method and disabling the first pool member in the list.
  6. From the
    Alternate
     and
    Fallback
     lists, select a static load balancing method, based on your network environment. Ensure that you select a load balancing method that does not take current server performance or connection load into account.
  7. In the Members area, for the
    Member List
     setting, from the
    Flags
     list, select a flag.
  8. Add wide IPs as members of this load balancing pool.
    The system evaluates the wide IPs (pool members) in the order in which they are listed. A wide IP can belong to more than one pool.
    1. From the
      Wide IP
       list, select a wide IP or type a name that matches an existing wildcard wide IP.
    2. In the
      Service
       field, type the name of a service or protocol.
    3. Click
      Add
      .
  9. Click
    Finished
    .

Creating a pool with pool type SRV

Create a SRV pool type in order to configure the BIG-IP system to load balance global traffic.
  1. On the Main tab, click
    DNS
    GSLB
    Pools
    .
    The Pool List screen opens.
  2. Click
    Create
    .
    The New Pool screen opens.
  3. In the General Properties area, in the
    Name
     field, type a name for the pool.
    Names must begin with a letter, and can contain only letters, numbers, and the underscore (_) character.
    The pool name is limited to 63 characters.
  4. From the
    Type
     list, select the
    SRV
     type.
  5. In the Members area, for the
    Load Balancing Method
     setting, from the
    Preferred List
    , select
    Round Robin
    .
    When deploying this implementation in a lab environment, to determine whether the BIG-IP system returns the DNS response that you expect, try selecting the
    Global Availability
     method and disabling the first pool member in the list.
  6. From the
    Alternate
     and
    Fallback
     lists, select a static load balancing method, based on your network environment. Ensure that you select a load balancing method that does not take current server performance or connection load into account.
  7. Add wide IPs as members of this load balancing pool.
    The system evaluates the wide IPs (pool members) in the order in which they are listed. A wide IP can belong to more than one pool.
    1. In the Members area, for the
      Member
       setting, from the
      Wide IP
       list, select a wide IP or type a name that matches an existing wildcard wide IP.
    2. In the
      Port
       field, type a port number.
    3. Click
      Add
      .
  8. Click
    Finished
    .

An example lw4o6 table

Following is an example of an lw4o6 binding table.
--------------------------
# text_csv
# psid_len 1
#
# IPv4                  IPv6 prefix         PSID
10.100.10.211,      2015:a000:0000:0000,     0,
10.100.10.211,      2015:a000:0000:0000,     1,
10.100.10.212,      2015:a000:0000:0001,     0,
10.100.10.212,      2015:a000:0000:0001,     1,
10.100.10.213,      2015:a000:0000:0002,     0,
10.100.10.213,      2015:a000:0000:0002,     1,
10.100.10.215,      2015:a000:0000:0003,     0,
10.100.10.215,      2015:a000:0000:0003,     1,
#end file

Creating a pool with pool type MX

Create a MX pool type in order to configure the BIG-IP system to load balance global traffic.
  1. On the Main tab, click
    DNS
    GSLB
    Pools
    .
    The Pool List screen opens.
  2. Click
    Create
    .
    The New Pool screen opens.
  3. In the General Properties area, in the
    Name
     field, type a name for the pool.
    Names must begin with a letter, and can contain only letters, numbers, and the underscore (_) character.
    The pool name is limited to 63 characters.
  4. From the
    Type
     list, select the
    MX
     type.
  5. In the Members area, for the
    Load Balancing Method
     setting, from the
    Preferred List
    , select
    Round Robin
    .
    When deploying this implementation in a lab environment, to determine whether the BIG-IP system returns the DNS response that you expect, try selecting the
    Global Availability
     method and disabling the first pool member in the list.
  6. From the
    Alternate
     and
    Fallback
     lists, select a static load balancing method, based on your network environment. Ensure that you select a load balancing method that does not take current server performance or connection load into account.
  7. Add wide IPs as members of this load balancing pool.
    The system evaluates the wide IPs (pool members) in the order in which they are listed. A wide IP can belong to more than one pool.
    1. In the Members area, for the
      Member
       setting, from the
      Wide IP
       list, select a wide IP or type a name that matches an existing wildcard wide IP.
    2. Click
      Add
      .
  8. Click
    Finished
    .

Creating a wide IP that provides for returning a response with an RCODE

Ensure that at least one global load balancing pool exists in the configuration before you create a wide IP.
Create a wide IP that provides for configuring a return code (RCODE) to return a response to the client when load balancing fails.
  1. On the Main tab, click
    DNS
    GSLB
    Wide IPs
    .
    The Wide IP List screen opens.
  2. Click
    Create
    .
    The New Wide IP List screen opens.
  3. From the General Properties list, select
    Advanced
    .
  4. In the
    Name
     field, type a name for the wide IP.
    You can use two different wildcard characters in the wide IP name: asterisk (*) to represent several characters and question mark (?) to represent a single character. This reduces the number of aliases you have to add to the configuration.
  5. From the
    Type
     list, select one of these record types for the wide IP:
    NAPTR
    The Name Authority Pointer record, NAPTR, aids in the standardization of Uniform Resource Names (URNs). NAPTR records map between sets of URNs, URLs and plain domain names, and suggest to clients the protocols available for communication with the mapped resource.
    A
    The Address record, or A record, lists the IP address for a given host name.
    SRV
    The Service resource record, SRV, is a pointer with which an alias for a given service is redirected to another domain.
    CNAME
    The Canonical Name resource record, CNAME, specifies an alias or nickname for the official, or canonical, host name.
    AAAA
    The IPv6 Address record, or AAAA record, lists the 128-bit IPv6 address for a given host name.
    MX
    The Mail Exchange resource record, MX, defines the mail system(s) for a given domain.
  6. From the
    Return Code On Failure
     list, select
    Enabled
    .
  7. From the
    RCODE
     list, select one of these options:
    NOERROR (No Error)
    No error condition.
    FORMERR (Query Format Error)
    The name server was unable to interpret the query.
    SERVFAIL (Server Failure)
    The name server was unable to process this query due to a problem with the name server.
    NXDOMAIN (Non Existent Domain)
    The domain name referenced in the query does not exist.
    NOTIMP (Not Implemented)
    The name server does not support the requested kind of query.
    REFUSED (Refuse To Answer)
    The name server refuses to perform the specified operation for policy reasons.
  8. Click
    Finished
    .
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