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.

Abstract

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.

Speaker

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.

Introduction

This is an intermediate, technical session. The primary audience is the technical managers of Internet domains, networks, mail hosts, and directories. Goals:

• Suggest some guidelines for naming and addressing
• Provide supporting technical background

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 different locations.

• 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 network-address-translating routers.
• 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 DNS-DHCP tools.
• Return unused or fragmented network address space to the IANA (BCP 4, currently RFC 1917).

• 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 informative

See 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.Com is a cluster service name pointing to a VMScluster of three hosts.
• Use CNAMEs sparingly, for deprecated names only.
• Delegate subdomains only if both necessary and possible.

• Use central naming (or an X.500 directory) to route mail.
• Position canonical names at the highest possible level in your domain.
• Offer central naming as an option for your entire organization.
• Use RFC 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 break ties:
  Stephen.L2.Arnold@Arnold.Com
• 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).

• 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 agent access.
• Use web client software (HTTP) for directory browsing. (See, for example http://Web500.Arnold.Com:8888.)
• 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!)

Stephen L. Arnold, Ph.D., President

Arnold Consulting
2530 Targhee Street, Madison, Wisconsin 53711-5491
Telephone: +1 608 278 7700
Facsimile: +1 608 278 7701

Stephen.L.Arnold@Arnold.Com
http://WWW.Arnold.Com

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