SENA UPSLink100 User Manual
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The IP address of the DNS server must be able to access the host site with the provided domain
name. The UPSLink provides the ability to configure the required IP addresses of both the Primary
and Secondary DNS servers addresses.
(The secondary DNS server is specified for use when the
primary DNS server is unavailable.)
4.1.2 Using DHCP
Dynamic Host Configuration Protocol (DHCP) is a communications protocol that lets network
administrators manage and automate the assignment of IP addresses centrally in an organization's
network.
DHCP allows the network administrator the ability to supervise and distribute IP addresses
from a central point and automatically send a new IP address when a computer i s plugged into a
different network location.
When in static IP mode, the IP address must be entered manually at each computer.
If a computer is
moved to another network location, a new IP address must be assigned. DHCP allows all the
parameters, including the IP address, subnet mask, gateway and DNS servers to be automatically
configured when the IP address is assigned.
DHCP uses a “lease” concept in assigning IP
addresses to a computer.
It limits the amount of time a given IP address will be valid for a computer.
All the parameters required to assign an IP address are automatically configured on the DHCP server
side, and each DHCP client computer receives this information when the IP address is provided at its
boot-up.
Each time a computer is reset, the UPSLink broadcasts a DHCP request over the network. The reply
generated by the DHCP server contains the IP address, as well as the subnet mask, gateway address,
DNS servers and the “lease” time. The UPSLink immediately places this information in its memory.
Once the “lease” expires, the UPSLink will request a renewal of the “lease” time from the DHCP server.
If the DHCP server approves the request for renewal, the UPSLink can continue to work with the
current IP address. If the DHCP server denies the request for renewal, the UPSLink will start the
procedure to request a new IP address from the DHCP server.
Note: While in DHCP mode, all network-related parameters for the UPSLink are to be configured
automatically, including the DNS servers. If the DNS server is not automatically configured, the user
may manually configure the settings by entering the primary and secondary DNS IP addresses.
To
force an automatic configuration of t he DNS address, set the primary and secondary DNS IP
addresses to 0.0.0.0 (recommended).
A DHCP sever assigns IP addresses dynamically from an IP address pool, which is managed by the
network administrator. This means that the DHCP client, i.e. the UPSLink, receives a different IP
address each time it boots up. The IP address should be reserved on the DHCP server side to assure
that the user always knows the newly assigned UPSLink address.
In order to reserve the IP address