OIT Networking & Monitoring Services

How to Move a Host Alias from One Host Database Entry to Another Host Database Entry

Sometimes a customer operating a device registered in the Host Database with a host alias needs to move that alias from one Host Database office entry to another.

For example, existing Host Database entry example1.princeton.edu may contain an host alias myserver.princeton.edu. (In DNS, myserver.princeton.edu points to canonical name example1.princeton.edu.) You wish to move the host alias myserver.princeton.edu to existing Host Database entry example2.princeton.edu. (In DNS, myserver.princeton.edu would instead point to canonical name example2.princeton.edu.)

This document outlines the procedures to accomplish this for most common cases.

To determine the best procedure to follow, answer these questions:

Question 1:
Does either Host Database entry example1.princeton.edu or example2.princeton.edu have an ENTRY-TYPE value of MAIL-ALIAS?

If so, proceed to Question 7. Otherwise, proceed to Question 2.

Question 2:
Are both Host Database entries example1.princeton.edu and example2.princeton.edu Dormnet subscriptions? (Dormnet subscriptions have names in the student.princeton.edu DNS domain.) If so, proceed to Question 4.

If both entries are Host Database office entries, proceed to Question 3.

If one entry is a Dormnet subscription, and the other entry is an an office entry, proceed to Question 7.

Question 3:
Is the alias myserver.princeton.edu at the top level of the princeton.edu DNS domain?

If so, proceed to Question 4. Otherwise (the alias is in a DNS subdomain, for example myserver.foo.princeton.edu), proceed to Question 7.

Question 4:
Does either Host Database entries example1.princeton.edu or example2.princeton.edu contain NETGROUP value of lockedhostdbentries?

If so, proceed to Question 7. Otherwise, proceed to Question 5.

Question 5:
Does Host Database entry example1.princeton.edu presently contain more than one host alias? That is, does it specify host aliases besides example1.princeton.edu?

If so, proceed to Question 7. Otherwise, proceed to Question 6.

Question 6:
Is it acceptable for the alias myserver.princeton.edu to not exist (in DNS and in the Host Database) for a brief time (say, several hours) while the alias is in the process of moving?

This is sometimes feasible when the alias myserver.princeton.edu is not used to provide a production service. For example, if it is an alias used only by you, or is used only for testing, there may be no one else who would be inconvenienced by having the alias myserver.princeton.edu not exist for a brief time.

If that's acceptable, proceed to Procedure A. Otherwise, proceed to Question 7.

Question 7:
Can the alias move at any time?

If so, proceed to Procedure B. Otherwise, if the alias needs to move at a particular date/time, proceed to Procedure C.


Procedure A

Your answers to the questions above have determined that the alias can be moved using the Host Database web forms. Do so as follows:

  1. Change entry example1.princeton.edu to remove the alias myserver.princeton.edu as follows:

    Wait for your change request to be processed before proceeding; the next step is not possible until your change request has been successfully processed. Email is sent to the entry's Technical Contacts for entry example1.princeton.edu showing when your change request is successfully processed.

  2. Change entry example2.princeton.edu to add alias myserver.princeton.edu as follows:

    Email is sent to the Technical Contacts for entry example2.princeton.edu showing when your change request is successfully processed.

Between the time that the alias is successfully removed from entry example1.princeton.edu and the time that the alias is successfully added from entry example2.princeton.edu, the alias doesn't exist.

Note that DNS changes are not instantaneous. Changes to DNS take time to propagate from the Host Database to DNS servers. And DNS information is cached by DNS servers and DNS clients. Until old DNS servers and clients that already have the old information cached have timed out that old information, some will continue to use the old information.

Taking this into account, when DNS information is affected by a Host Database change, it can take up to 16 hours before the last DNS client has stopped using the old DNS information.

This interval can be reduced to 4 hours if the Host Database entry example1.princeton.edu is temporarily changed to have its DNS Time To Live (TTL) reduced in advance of the DNS changes to move the alias. If you feel this is necessary, at least four full business days before you plan to move the alias, send email to hostmaster@princeton.edu to request reduction of the DNS TTL for example1.princeton.edu. After you have moved the alias, send email to hostmaster@princeton.edu to request that the DNS TTL for example1.princeton.edu be returned to normal.

Procedure B

Your answers to the questions above have determined that the alias can move at any time, but cannot be moved using the Host Database web forms. OIT staff will need to make the changes for you manually.

Send email to hostmaster@princeton.edu asking that alias myserver.princeton.edu be moved from entry example1.princeton.edu to example2.princeton.edu. Do not specify any specific date/time that the alias should move.

The information here about authorization to change Host Database entries and processing time for manual handling applies.

Procedure C

Your answers to the questions above have determined that the alias cannot be moved using the Host Database web forms, and must be moved at a particular date/time.

OIT staff will need to make the changes for you manually as a "Scheduled Host Database Change."

This kind of change is the most complex case. See the detailed instructions at Scheduling a Host Database Change For a Specific Time.


A service of OIT Networking & Monitoring Services
The Office of Information Technology,
Princeton University
Last Updated: September 5 2013