Planning and Configuring HP DCE 1.8

Chapter 7 149
Notes on Cell Administration
Establishing Intercell Communication
Establishing Intercell Communication
The information in this section supplements the information in the OSF
DCE Administration Guide - Core Services , and describes how
intercell communication should be configured inan HP-UX environment.
Communication between DCE cells is facilitated by the gdad daemon,
which implements the Global Directory Agent (GDA). When a client in a
local cell wants to access another cell that the local cell does not already
recognize, the request is passed to gdad, which looks up and returns
information about how to find the remote cell. This information is
cached, so that gdad is not asked repeatedly for the same information.
gdad finds information about the remote cell by querying a Domain
Name Service (DNS) database. DNS is not part of DCE; it is a widely
used distributed naming service, implemented on HP-UX by the named
daemon, and documented in named (1M) man page and in Internet
RFCs 1032, 1033, 1034, and 1035.
These procedures describe configuring GDA so that it can find the DNS
server or servers where cell information is stored, creating DNS
"resource records" that describe the cells you want GDA to be able to
locate, and establishing peer-to-peer trust between two cells.
Specifying DNS Servers that GDA Should Query
GDA must be told which DNS name servers (such as instances of
named) to query for information about foreign cells. The name server at
localhost is usually preferred, as only localhost provides recursive query
service—if localhost doesn't have the requested data, localhost will query
other name servers until it either finds the requested data or exhausts
the list of name servers that it knows about.
Using localhost reduces the requirement to keep GDA informed when
name server configurations change, and allows GDA to always receive a
response with a single query. In some environments, however, you may
want to point GDA at a non-local server or servers, rather than at
localhost.
gdad uses the following algorithm to identify which name server or
name servers to query:
1. gdad first reads the file /etc/opt/dce/named.ca, which, if present,