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noctonura
Asked: 2016-03-16 13:18:26 +0800 CST

How should a long-lived connection behave when there is a DNS change?

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Scenario:

  1. Connector.com connects to server.net, which resolves to 20.30.40.50
  2. Connector.com and 20.30.40.50 keep the connection open
  3. DNS is updated so that server.net now resolves to 7.8.9.10

Should Connector.com recognize that server.net now resolves to something different and open a new connection? How should this be handled?

domain-name-system

2 Answers

  1. Best Answer

    Should Connector.com recognize that server.net now resolves to something different and open a new connection?

    Usually not. DNS is only used to find the address for a specific name but the association (TCP connection) is between two IP addresses and not between two hostnames.

    It still might be that your application requires a different behavior. But this would be application logic then and will vary depending on the requirements of the specific application.

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  2. Q: Should Connector.com recognize that server.net now resolves to something different and open a new connection?

    A: No.

    If you wanted Connector.com to establish a new connection you'd have to terminate the existing connection, flush its DNS cache, flush the DNS cache of its upstream DNS servers and make a new connection.

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