RFC 1279 (rfc1279) - Page 2 of 15

X

RFC 1279                X.500 and Domains                November 1991


    University College London, GB

This type of structure is termed ``organisational X.500''.  This is a
subset of the general capabilities.


3  The basic model

    X.500 has as much relation to the DNS as DNS has to ARP. Paul
    Mockapetris


This is, essentially, the position adopted here.  The basic model is
that organisational X.500 is providing a layer of naming at the level
above domain names.  These structured names can be considered to form
a naming layer above domain names.  There are the following key
differences:

 o  Organisational X.500 tends to use longer and more descriptive
    values

 o  The organisational X.500 DIT is slightly shallower than the DNS
    tree

 o  X.500 has a richer information framework than DNS


These differences suggest that the following should NOT be done:

 o  Represent X.500 information in the DNS

 o  Have an algorithmic mapping between the two hierarchies

This note proposes to represent DNS information in the DIT, and to
provide for a loose coupling between the two trees.  This note does
not propose an equivalencing of X.500 and Domains.

The proposed model is illustrated in Figure 1.  Both an organisational
and domain structure is represented in the DIT, by use of appropriate
object classes and attribute types.  A weak linkage is provided
between the two parts of the tree by use of special attributes.  Here,
the linkage is 1:1, but it may be more complex for some parts of the
organisational DIT or domain namespace.  The linkage is achieved by
use of special attributes, as described in Section 11.

Hardcastle-Kille