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101 · Question #52

A virtual server is listening at 10.10.1.100:any and has the following iRule associated with it: when CLIENT_ACCEPTED { if {[TCP::local_port] equals 80 } { pool pool1 } elseif {[TCP::local_port] equal

The correct answer is D. Unknown. The pool cannot be determined from the information provided.. When a connection arrives on a port not matched by any iRule branch, the outcome depends on whether the virtual server has a default pool configured, which is not stated in the question.

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Question

A virtual server is listening at 10.10.1.100:any and has the following iRule associated with it:

when CLIENT_ACCEPTED { if {[TCP::local_port] equals 80 } { pool pool1 } elseif {[TCP::local_port] equals 443 } { pool pool2 } If a user connects to 10.10.1.100 and port 22, which pool will receive the request.

Options

  • Apool1
  • Bpool2
  • CNone. The request will be dropped.
  • DUnknown. The pool cannot be determined from the information provided.

How the community answered

(28 responses)
  • A
    11% (3)
  • B
    7% (2)
  • C
    21% (6)
  • D
    61% (17)

Why each option

When a connection arrives on a port not matched by any iRule branch, the outcome depends on whether the virtual server has a default pool configured, which is not stated in the question.

Apool1

pool1 is only selected when TCP::local_port equals 80; port 22 does not satisfy that condition.

Bpool2

pool2 is only selected when TCP::local_port equals 443; port 22 does not satisfy that condition.

CNone. The request will be dropped.

Dropping the request would only be certain if no default pool is configured on the virtual server, but the question does not confirm that, so 'dropped' cannot be stated as a definitive outcome.

DUnknown. The pool cannot be determined from the information provided.Correct

The iRule only handles ports 80 and 443 explicitly; port 22 matches neither branch, so no pool is selected by the iRule itself. However, BIG-IP will use the virtual server's default pool if one is configured, and the question does not state whether a default pool exists. Because that configuration detail is absent, the receiving pool cannot be determined from the information provided.

Concept tested: CLIENT_ACCEPTED iRule port-based pool selection fallback

Source: https://clouddocs.f5.com/api/irules/TCP__local_port.html

Topics

#iRules#CLIENT_ACCEPTED#TCP port matching#pool selection logic

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