Managing The Host Table - Nortel 5399 User Manual

Book A

Managing the Host Table

Model 5399 Remote Access Concentrator Network Administrator's Guide for UNIX
The host table contains this information for each host:
• Host name.
• Aliases (if any).
• IP address.
• Multiple IP addresses (if any).
• System status (if the entry is updated by RWHO).
• Load factor (if the entry is updated by RWHO).
• Number of users (if the entry is updated by RWHO).
The CLI hosts command displays all entries in the host table. The
5399 RAC can build and update the host table from RWHO messages
and from responses to DNS and/or IEN-116 queries. Entries are updated
according to information received. Information for a host will be updated
if new information received is different from what is currently in the host
table. The 5399 RAC considers information from a DNS server the most
reliable source; it considers an IEN-116 as the next reliable source; and
it considers RWHO broadcasts as the least reliable source. Thus,
information from a DNS server always updates current information
received from either an IEN-116 server or an RWHO broadcast;
information from an IEN-116 server always updates current information
received from an RWHO broadcast.
The 5399 RAC also deletes entries. The criteria for deletion depend on
the source of the entry. Each DNS response includes a time to live (TTL).
When an entry reaches its full life (default=60 minutes), the DNS server
is queried again. If a DNS server recognizes the name, the entry is
re-entered in the host table; otherwise, it is deleted. The 5399 RAC keeps
track of how often each IEN-116 host table entry is referenced. If a name
server entry has not been used for 32 days, it is deleted.
Chapter 1 Network Administration
A-47