Node and Host Name Sizes on HP-UX: Using the Expanded Capabilities of HP-UX

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APPENDIX A: Rules for Constructing Host and Node Names
This appendix describes some rules, established by Internet standards bodies, for the formation of
host names.
The Domain Name Service (DNS), as documented in RFC 1034, limits a fully qualified host name to a
total of 255 octets (bytes). A name is composed of labels separated by dots (.) where each label is
limited to 63 octets. A label can be composed of letters, digits, and hyphens (-). Letters are treated in
a case-insensitive manner. A label cannot start with the hyphen. It is unclear whether a label can
start with a digit, so do so only with caution.
System administrators usually set the host name on the system to just the first label (without dots). This
is generally more convenient for users and applications. This is considered a “relative” name (that is,
relative to its Internet domain).
HP strongly recommends that you set the system node name to the same value as the first label set in
the system host name. This is because many programs use the node name as the Internet host name.
For example, if the host name is set to sys.x.y.z, the node name should be set to sys. In this way
node names will not be more than 63 bytes for systems with host names that conform to the
standards.
The following table provides additional examples:
Host Name Node Name
jims-test-system.dev.xyzco.com jims-test-system
payrollsystem1 payrollsystem1