Dns Resolver; Dns Server; Public And Private Networks And The Use Of Napt - Efficient Networks SpeedStream 5600 Series Installation Manual

distinct DNS functions provided by the router: the DNS resolver and the

DNS server.

DNS Resolver

The DNS resolver is the entity that creates a DNS request for transmission
to a DNS server (which may be co-located in the router or be an external
DNS server). The DNS resolver is only used by certain user interface
commands that allow a hostname argument as well as an IP address
argument.
The DNS resolver requires the user to configure a single DNS server IP
address to which to direct DNS requests. This IP address may be the
router itself in the situation where the DNS server is enabled on the router
or it may be any reachable IP address at which a DNS server is available.
DNS Server
The DNS server is the entity that responds to DNS requests. The DNS
server provides IP address-to-hostname resolution and hostname-to-IP
address resolution for LAN clients via DNS requests. It may also be
configured to provide this service for WAN clients. The DNS server also
supports hostname-to-IP address resolution for user interface commands
where appropriate in response to requests submitted by the DNS resolver.
The DNS server is enabled by default from the factory and provides the
router with the default hostname "speedstream".
Public and Private Networks
and the use of NAPT
An IP address must be unique among all networks reachable from a given
host using the IP protocols. The United States Internet Registry ensures
the uniqueness of the IP addresses on the Internet. The Internet Registry
assigns an entire IP network number to each site connected to the Internet.
Each IP address at a site is unique as long as the site assigns a different
host number to each host on its network. Thus each host is ensured a
globally unique IP address that is known as a public IP address.
However, there has been concern over the eventual exhaustion of the
public address space. This has led the Registry to set aside IP network
numbers for private addressing. These numbers are not assigned to anyone
by the Internet Registry and are open for use by any site. IP addresses are
Efficient Networks, Inc. Technical Concepts 33