User`s guide

KwikNet Low Level Services
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DHCP Timeout
If no response is received from any DHCP or BOOTP server within the timeout interval
(initially four seconds), the DHCP client resends its broadcast query and increases its
timeout interval by a factor of 2
n
where n is the number of failed attempts thus far. The
retry timeout value is not allowed to exceed an upper limit of 64 seconds. If an IP
address cannot be acquired, the DHCP client keeps retrying for approximately three
minutes after which the cycle is repeated. This process continues forever if an IP address
cannot be found.
DHCP Leases
When a DHCP server provides an IP address, it grants the network interface a lease to
use that address for a specific interval. The DHCP client always requests a permanent
lease but can live with a limited lease interval if that is all that is granted by the DHCP
server. Note that the lease granted by a BOOTP response is considered to be permanent.
The DHCP client always tries to renew a limited time lease by negotiating with the
DHCP server which granted the lease. The DHCP server dictates when the lease will
expire and can specify the points in time at which the lease renewal should be attempted.
By default, in the absence of contrary directions from the DHCP server, the DHCP client
will attempt to renew its lease as follows. If the lease interval is L seconds, the DHCP
client begins a lease renewal negotiation after L/2 seconds. Negotiation requests are
repeated at intervals until 7L/8 seconds into the lease. Each interval is half the period
from the time of the last request to the 7L/8 seconds mark, but never less than 60
seconds.
If a new lease is not granted, the DHCP client will initiate a new negotiation sequence by
broadcasting a query to all DHCP servers requesting the use of the expired IP address. If
the request is not granted by any server, the DHCP client starts over, trying once again to
acquire the initially configured IP address, if any, from any DHCP server.
DNS Server Identification Via DHCP
When a DHCP server responds to an IP address query, it can also provide a list of IP
addresses for known Domain Name System (DNS) servers. The DHCP client accepts up
to two DNS server IP addresses. The first member of the list is deemed the primary DNS
server; the second is the secondary DNS server. The server addresses are recorded and
can be accessed by your application for presentation to your
KwikNet DNS Client, if it
exists. To access the DNS server information, call Treck function
tfConfGetBootEntry().