SEMESTER 2 Chapter 8
The Routing Table: A Closer Look
V 4.0
8.1.2.1
8.1.3.1
8.1.3.3
8.1.3.4
8.1.4.1
8.1.4.2
8.1.4.3
8.1.4.5
8.1.5.1
8.1.5.2
What are the three types of
routes found in the routing
table?
What happens as soon as the
no shutdown command is
entered after the interface is
configured?
What is a level 1 route?
Directly connected networks
Static routes
Dynamic routing protocols
The route is added to the routing table
a route with a subnet mask equal to or less than the
classful mask of the network address
What are the three functions a
Default route - A default route is a static route with the
level 1 route can have?
address 0.0.0.0/0.
Supernet route - A supernet route is a network address
with a mask less than the classful mask.
Network route - A network route is a route that has a
subnet mask equal to that of the classful mask. A
network route can also be a parent route. Parent routes
will be discussed in the next section
What are the three sources of a directly connected network, static route, or a dynamic
level 1 route?
routing protocol
What can a level 1 route be
Ultimate route
further defined as?
What does the above include?
either a next-hop IP address (another path)
and/or an exit interface
What is the difference between The parent does not contain any next-hop IP address
a parent and child route?
or exit interface information
What is a level 1 parent route? a network route that does not contain a next-hop IP
address or exit interface for any network
When is a parent route
automatically created any time a subnet is added to the
created?
routing table
What is a level 2 route?
a route that is a subnet of a classful network address
What can be the source of a
a directly connected network, a static route, or a
level 2 route?
dynamic routing protocol
What is the level 2 child route? the specific route entry for the 172,16.3.0/24 subnet
Where is the subnet mask
In the parent route
listed?
Why are level 2 routes
they will contain the next-hop IP address and/or exit
considered ultimate routes?
interface
What happens if all the child
The parent route is removed
routes are removed?
What happens to the routing
The subnet mask for each child route will be displayed
table when child routes are in
different subnets using VLSM?
What happens to the parent
The classful subnet mask is displayed
subnet mask when classless
8.2.1.2
8.2.2.1
8.2.2.3
8.2.2.4
8.2.3.1
8.2.3.2
8.2.3.3
8.2.3.4
8.3.1.1
8.3.1.2
8.3.2.1
8.3.2.2
8.3.4.1
8.3.4.2
routing is used?
What else is stated in the
parent route?
We will go over this in class.
What is the definition of best
match?
What is always true of the
preferred route?
What has to happen before a
child route is examined?
Why is the level 1 ultimate
route used in the example?
What process happens after
that route is selected?
What must happen before any
level 2 child routes are
examined for a match?
What happens in step 2 of the
route lookup process?
How many bits much match for
that route to be selected?
What happens if the router
does not find a match?
When is a child route checked
when using VLSM?
What is the only difference
when using VLSM?
What do classful and classless
routing behaviors determine?
What are the two routing
behaviors listed?
What type of routes can be
used to overcome the
limitations of RIPv1?
What happens at step three if a
classful routing protocol is
being used?
What level are the commands
no ip classless and ip classless
entered at?
What happened beginning with
the IOS version 11.3?
What happens at step three if a
classless routing protocol is
being used?
What happens if there is now a
lesser match with a level 1
Variably subnetted
the route in the routing table that has the most number
of left-most matching bits with the destination IP
address of the packet.
The route with the most number of equivalent left-most
bits, or the longest match.
there must be at least a match between the destination
IP address of the packet and the classful address of
the parent route
It is the best match
A recursive lookup is done for the destination ip
address
there must first be a match between the classful
address of the level 1 parent route and the destination
IP address of the packet
the level 2 child routes will be examined for a match
24
The packet is discarded
After a match with the parent route.
The child routes contain their own subnet masks.
how the routing table is searched after it is populated
ip classless
no ip classless
Static routes
The packet is dropped
Global configuration
Ip classless became the default setting
continue searching level 1 supernet routes in the
routing table for a match, including the default route, if
there is one
It forwards the packet
8.3.5.2
8.3.5.3
supernet or default routes?
What happens if there is not a
match with any route in the
routing table?
What is true about the default
route in a classless routing
behavior?
What is the recommendation
for today’s networks?
The router drops the packet
the lowest-bit match. In classless routing behavior, if no
other route matches, the default route will match.
use classless routing behavior so that supernet and
default routes can be used whenever needed