configuration on all the devices in the network. Instead
of having to configure several different DNS server IP
addresses for redundancy purposes, in IPv6, a single
address, the anycast address, can be configured on all
DNS clients. As long as at least one of the DNS servers
that have been configured as part of the anycast group is
online, DNS redundancy is guaranteed.
Routing
Routing is the process of selecting a path through a
network. This functionality is performed by routers,
which are devices made to interconnect networks, find
the best paths for data packets from their source toward
their destination, and route data based on a routing
table. As switches have a critical role at Layer 2 in
connecting devices in the same physical area and
creating local-area networks, routers have a critical role
at Layer 3 in interconnecting networks and creating
wide-area networks. The main functions of a router are
the following:
Path determination
Data packet routing or forwardingPath determination is the process through which routers
look up information in their routing tables to determine
where to forward the data packets received on their
interfaces. In a typical scenario, a router has at least two
interfaces—and usually more. Each interface connects to
a Layer 3 network, which means the interface on the
router is configured with an IP address in that network.
In most cases, the router acts as the default gateway for
that Layer 3 network, meaning that any traffic that is not
destined for the local network will be forwarded to the
router, and the router will forward it further toward its
destination. Each router maintains its own routing table,
which contains a list of all the destinations or networks
that are known to the router and how to reach those
destinations. When receiving a packet on one of its