Internet and Mail Naming and Addressing Suggestions for
Internet and Mail Naming and Addressing Suggestions for Large Organizations Stephen L. Arnold, Ph.D.
President, Arnold Consulting
Presented 3 November 1997 at the DECUS U.S. Chapter Symposium in
Anaheim, as Session MM004.
A recurring need in large organizations is to easily and unambiguously
identify networked devices, electronic mailboxes, and other
paraphernalia of the information age. While each situation is
different, there is no need to repeat every mistake yourself! The
speaker shares his experiences connecting clients with thousands of
mailboxes and personal computers to the Internet.
Dr. Stephen L. Arnold is an independent consultant with over 14 years
of networking experience on OpenVMS, UNIX, and IBM mainframe and
midrange systems. Steve specializes in internetworking, electronic
mail, and directory services.
This is an intermediate, technical session. The primary audience is the
technical managers of Internet domains, networks, mail hosts, and
Suggest some guidelines for naming and addressing
Provide supporting technical background
Names, Addresses, and Routes
These concepts are not the same!
Radia Perlman's definitions:
If host X is to communicate with host Y
"Y" is a name if: "Y" continues
to work, even if host Y moves; and "Y" works for any
host X, regardless of host X's location.
"Y" is an address if: "Y"
changes if host Y moves; and "Y" works for any host X,
regardless of host X's location.
"Y" is a route if: "Y" changes
if host Y moves; and "Y" is different for X's in
Don't use addresses where names are allowed.
Don't use addresses for names.
Used CIDR addresses ( RFC 1519) provided by
your Internet service provider for your border (or entire) network.
Use network addresses reserved for private internets (BCP 5,
currently RFC 1918)
behind application- or circuit-relay firewalls or
Renumber your networks, and prepare to renumber again in the future
( RFC 1900, RFC 2071, RFC 2072).
Use DHCP to assign most addresses. Consider using integrated
Return unused or fragmented network address space to the IANA (BCP
4, currently RFC
General Naming Suggestions
Use shallow, wide name spaces.
Use neutral names.
Prefer geographical subunits over organizational subunits.
Display names in mixed case, as the owner prefers.
Almost always allowed Less provincial More readable More
Choosing a Name for Your Computer, FYI 5 (currently RFC 1178), for
additional suggestions and rationale. See RFC 2100 for a
relevant April Fool's Day poem.
Domain Name Suggestions
Make names short.
Use only letters, digits, and dashes ( RFC 952).
Create application domain names for servers: WWW, FTP,
mail, IMAP, LDAP, NS (BCP 17, currently RFC 2219).
Use A records for mail host names, not MX records. You can't
MX to another MX.
Offer homogeneous, highly available services. Example:
LDAP.Arnold.US is a cluster service name pointing to a VMScluster of
Use CNAMEs sparingly, for deprecated names only.
Delegate subdomains only if both necessary and possible.
Mailbox Naming Suggestions
Use central naming (or an X.500 directory) to route mail.
Position canonical names at the highest possible level in your
Offer central naming as an option for your entire organization.
1327-compliant canonical names:
givenname.mi.surname@domainname Don't use generational
qualifiers or other attributes.
Use only characters that need not be quoted: A-Z, a-z, 0-9,
apostrophe, and hyphen.
Use middle initials or subdomains to get more name space.
Use the digits 2-9 as synthetic middle "initials" to
Prefer formal given names.
Make common names in mailboxes consistant with paper telephone
books, on-line directories, and business cards.
Support standard and frequently-used role mailboxes: Postmaster,
Hostmaster, Webmaster, etc. ( RFC 2142).
OSI Naming Suggestions
Get organizational identifiers. In the United States: Large
organizations: Register numeric and alphanumeric organizational identifiers
with ANSI ($2500).
Others: Use your organization name, as registered with your state (no
charge). If you use X.400 mail: Register an MHS management domain name
with ANSI ($500).
Register only in the country of your home office.
Don't use unnecessary name attributes.
Ask your X.400 service provider about ADMD=single space.
Use only the X.500 Directory.
Do not confuse X.400 addresses with X.500 distinguished names.
Keep your X.500 project secret until roll-out.
Get permission from entry owners before serving directory
information to the Internet White Pages or the Web.
Support all the data objects in the Internet White Pages schema ( RFC 2218).
Use the light-weight directory access protocol (LDAP) for mail user
Use web client software (HTTP) for directory browsing. (See, for
Join the Internet White Pages project and serve some entries!
Beware of "LDAP-only" servers.
Avoid directory synchronization by using distributed directories.
(There's more advice in the next
session on that topic!)
Steve Arnold, Ph.D., President
2530 Targhee Street, Fitchburg, Wisconsin 53711-5491
Telephone: +1 608 278 7700
Facsimile: +1 608 278 7701
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