Considerations for DNS Host Name Aliases

These DNS Host Name Alias standards are:

• used with disaster recovery procedures to coordinate fail-over resources
• used with disaster recovery procedures to eliminate resource conflicts
• used with high availability procedures to coordinate fail-over resources
• used with high availability procedures to eliminate resource conflicts
• used with manual fail-over procedures to coordinate fail-over resources
• used with manual fail-over procedures to eliminate resource conflicts
• consistent and repeatable procedures
• compatible with standalone, high availability, disaster recovery, business continuity, and virtualized environments

Multiple DNS Aliases may be configured to point to a host name, and these aliases may consist of a variable number of characters, and be names requested by the users or application administrators. However, each DNS alias MUST be an Enterprise Wide Unique (EWU) value to eliminate conflicts during outages, fail-overs, tests, etc. It is recommended that at least one DNS Alias be created using the resource group name which will be used for fail-over procedures.

The reason for using DNS aliases rather than host names is for ease of configuration during fail-overs, either planned or unplanned. Aliases allow the system administrator to easily and quickly redirect users to desired business functions anywhere in the enterprise. This does not require changing IP addresses or renaming resources on any system. It is a simple DNS change and business functions become available. This is especially useful during disaster recovery testing and implementations where fail-over resources may be already provisioned and attached to a network in a remote location. A DNS alias permits the system administrator to point users from one data center to another to reacquire business functions.

The DNS alias name based on the RG name shall consist of exactly 8 characters as shown in table 1:

Table 1: DNS Alias Name Structure based on RG Name

Application Code	+	Environment	+	Function	+	Company	+	RG Sequence ID
3 char	+	1 char	+	1 char	+	2 char	+	1 char

Table 1 illustrates the structure for a DNS Alias naming standard. This structure identifies a DNS Alias name that is 8 characters in length and corresponds with the resource group name associated with this DNS Alias. Some example DNS Alias names are illustrated in Table 2.

Table 2: Example DNS Alias Names

Application Code	Environment	Function	Company Code	Sequence ID	Example Resource Group Name	Example DNS Alias Name
ora	p	d	mx	0	orapdmx0	orapdmx0
ora	p	d	mx	1	orapdmx1	orapdmx1
db2	a	d	ib	0	db2adib0	db2adib0
tib	t	a	hp	8	tibtahp8	tibtahp8
web	d	a	ib	4	webdaib4	webdaib4
apa	a	a	ci	3	apaaaci3	apaaaci3
pag	p	u	mx	0	pagpumx0	pagpumx0

The policies, guidelines, standards, and procedures set forth in this document for your consideration are as follows:

Policies:

• All DNS Alias names shall be Enterprise Wide Unique values.
• At least one DNS Alias name will be defined per system for user and application access, whose name will correspond with the resource group name
• DNS Alias names shall use alpha-numeric characters only

Guidelines:

• More than one DNS alias may be configured per system, depending upon the user and application requirements, however any additional alias names must also be Enterprise Wide Unique values.

Standards:

• This document defines a DNS alias naming standard.

Procedures:

• Implementation of this standard requires access to the enterprise DNS, and the ability to create CNAME records. This duty may be delegated to a DNS administrator.