Module 15 - Router & Routing
How is the destination network in an IPv6 static route identified?
Using an IPv6 prefix and prefix length
Which IPv4 static route statement is true?
Using the exit interface only is common in a point-to-point configuration
What type of static route is created when the next-hop IP address and exit interface are specified?
fully specified static route
This example shows the show ipv6 route static command output to display the contents of the routing table. Notice that the static default route configuration uses the ___ mask for IPv4 default routes and the ___ prefix for IPv6 default routes. Remember that the IPv4 subnet mask and IPv6 prefix-length in a routing table determines ___. A /0 mask or ::/0 prefix indicates that ___. As long as a more specific match does not exist, the default static route matches ___.
/0, ::/0, how many bits must match between the destination IP address of the packet and the route in the routing table, none of the bits are required to match, all packets
What network address and subnet mask combination would be used to create a default static route that matches any IPv4 destination?
0.0.0.0 0.0.0.0
The command syntax for an IPv4 default static route is similar to any other IPv4 static route, except that the network address is ___ and the subnet mask is ___. The 0.0.0.0 0.0.0.0 in the route will ___
0.0.0.0, 0.0.0.0, match any network address.
By default, static routes have an administrative distance of ___, making them preferable to routes learned from dynamic routing protocols.
1
The static route uses a destination IP address and a ___ mask for IPv4 host routes, and a ___ prefix length for IPv6 host routes.
255.255.255.255 (/32), /128
A host route is an IPv4 address with a ___, or an IPv6 address with a ___
32-bit mask, 128-bit mask
The command syntax for an IPv6 default static route is similar to any other IPv6 static route, except that the ipv6-prefix/prefix-length is ___, which matches all routes.
::/0
The following shows the three ways a host route can be added to the routing table:
Automatically installed when an IP address is configured on the router (as shown in the figures) Configured as a static host route Host route automatically obtained through other methods (discussed in later courses)
This is in addition to the connected route, designated with a ___ in the routing table for the ___ of the interface.
C, network address
What command, or set of commands, would be used to determine if the following configuration on router HQ works as designed? ip route 0.0.0.0 0.0.0.0 serial 0/0/0 10 ip route 0.0.0.0 0.0.0.0 serial 0/1/0
HQ(config)# interface serial 0/1/0 HQ(config-if)# shutdown HQ(config-if)#end HQ# show ip route
When configuring a static route, the next hop can be identified by an ___, ___, or ___.
IP address, exit interface, both
There is a situation in IPv6 when a fully specified static route must be used. If the IPv6 static route uses an___
IPv6 link-local address as the next-hop address, use a fully specified static route.
The reason a fully specified static route must be used is because ___. Link-local addresses are only unique on a ___. The next-hop link-local address may be a valid address on ___. Therefore, it is necessary that the ___ be included.
IPv6 link-local addresses are not contained in the IPv6 routing table, given link or network, multiple networks connected to the router, exit interface
What is the purpose of a floating static route?
It allows an alternate connection to be used when the preferred link fails
What is a characteristic of a default static route?
It identifies the gateway IP address to which the router sends all IP packets for which it does not have a learned or static route
How the destination is specified creates one of the three following types of static route:
Next-hop route - Only the next-hop IP address is specified Directly connected static route - Only the router exit interface is specified Fully specified static route - The next-hop IP address and exit interface are specified
IPv4 Starting Routing Tables
R1 can ping R2 because the router has entries only for the directly connected networks and associated local addresses. R1 cannot ping R3 LAN because R1 does not have an entry in its routing table for R3 LAN network
Which IPv6 static route would serve as a backup route to a dynamic route learned through OSPF?
Router1(config)# ipv6 route 2001:db8:acad:1::/32 2001:db8:acad:6::2 200
Static routes can be configured for IPv4 and IPv6. Both protocols support the following types of static routes:
Standard static route Default static route Floating static route Summary static route
R1# show running-config | section ip route
This command filters the running configuration for only IPv4 static routes.
R1# show running-config | section ipv6 route
This command filters the running configuration for only IPv6 static routes.
R1# show ip route 192.168.2.1
This command will show output for only the specified network in the routing table.
R1# show ipv6 route 2001:db8:cafe:2::
This command will show output for only the specified network in the routing table.
R1# show ip route static | begin Gateway
This output shows only the IPv4 static routes in the routing table. Also note where the filter begins the output, excluding all the codes.
R1# show ipv6 route static
This output shows only the IPv6 static routes in the routing table. Also note where the filter begins the output, excluding all the codes.
A network administrator is configuring a route to forward packets to a specific web server. What type of route should be configured by the administrator?
a host route
A host route allows ___
a router to efficiently determine when it receives a packet for the interface instead of being forwarded
The difference between an Ethernet multi-access network and a point-to-point serial network is that a point-to-point serial network has ___, the router at the ___. With Ethernet networks, there may be ___, including hosts and even multiple routers.
only one other device on that network, other end of the link, many different devices sharing the same multi-access network
When an active interface on a router is configured with an IP address, a local host route is ___ The local routes are marked with ___ in the output of the routing table.
automatically added to the routing table, L
The show ip route static command output from R1 displays the contents of the static routes in the routing table. Note the asterisk (*) next to the route with code 'S'. As displayed in the codes table in the show ip route output, the asterisk indicates that this static route is a ___, which is why it is selected as the ___. Notice that the static default route configuration uses the ___ mask for IPv4 default routes. Remember that the IPv4 subnet mask in a routing table determines ___. A /0 mask indicates that ___. As long as a more specific match does not exist, the default static route matches ___
candidate default route, Gateway of Last Resort, /0, how many bits must match between the destination IP address of the packet and the route in the routing table none of the bits are required to match, all packets
Routers commonly use default routes that are either ___ or learned from another router, using a ___.
configured locally, dynamic routing protocol
Default static routes are commonly used when ___, or a ___
connecting an edge router to a service provider network, stub router (a router with only one upstream neighbor router).
A host route can be a manually configured static route to ___
direct traffic to a specific destination device
Which type of static route that is configured on a router uses only the exit interface?
directly connected static route
IP floating static routes are configured by using the ___ argument to specify an administrative distance. If no administrative distance is configured, the default value ___ is used.
distance, 1
When configuring a static route, another option is to use the ___ to specify the next-hop address.
exit interface
In a fully specified static route, both the ___ and the ___ are specified. This form of static route is used when the ___.
exit interface, next-hop IP address, exit interface is a multi-access interface and it is necessary to explicitly identify the next hop
In a fully specified IPv6 static route, both the ___ and the ___ are specified.
exit interface, next-hop IPv6 address
A default route does not require any ___ to match between the ___ and the ___.
far-left bits, default route, destination IP address
Which type of static route typically uses the distance parameter in the ip route global configuration command?
floating static route
To accomplish this, the floating static route is configured with a ___ than the primary route. The administrative distance represents the ___. If multiple paths to the destination exist, the router will choose the path with the ___.
higher administrative distance, trustworthiness of a route, lowest administrative distance
The administrative distance of a static route can be ___ to make the route ___ than that of another static route or a route learned through a dynamic routing protocol. In this way, the static route ___ and is not used when the route with the better administrative distance is active.
increased, less desirable, "floats"
Cisco IOS automatically installs a host route, also known as a local host route, when an ___
interface address is configured on the router
Static routes are configured using the ___ and ___ global configuration commands.
ip route, ipv6 route
What is the correct syntax of a floating static route?
ip rute 209.165.200.228 255.255.255.248 10.0.0.1 120
Which static route statement shows a recursive IPv6 static route?
ipv6 route 2001:db8:cafe:1::/56 2001:db8:1000:10::1
Which command would create a valid IPv6 default route?
ipv6 route ::/0 2001:db8:acad:2::a
The ___ global configuration command must be configured to enable the router to forward IPv6 packets.
ipv6 unicast-routing
The table shows the various ipv6 route command parameters and their descriptions.
ipv6-prefix Identifies the destination IPv6 network address of the remote network to add to the routing table. /prefix-length Identifies the prefix length of the remote network. ipv6-address Identifies the next-hop router IPv6 address. Typically used with broadcast networks (i.e., Ethernet) Could create a recursive static route where the router performs an additional lookup to find the exit interface. exit-intf Identifies the exit interface to forward packets. Creates a directly connected static route. Typically used in a point-to-point configuration. exit-intf ipv6-address Creates a fully specified static route because it specifies the exit interface and next-hop IPv6 address. distance Optional command that can be used to assign an administrative distance value between 1 and 255. Typically used to configure a floating static route by setting an administrative distance that is higher than a dynamically learned route.
For IPv6 static routes, the next-hop address can be the ___ of the adjacent router. However, you must specify an ___ and an ___ when using a link-local address as the ___, as shown in the example. First, the original IPv6 static host route is removed, then a fully specified route is configured with the IPv6 address of the server and the IPv6 link-local address of the ISP router.
link-local address, interface type, interface number, next hop
The table describes the ip route command parameters.
network-address Identifies the destination IPv4 network address of the remote network to add to the routing table. subnet-mask Identifies the subnet mask of the remote network. The subnet mask can be modified to summarize a group of networks and create a summary static route. ip-address Identifies the next-hop router IPv4 address. Typically used with broadcast networks (i.e., Ethernet). Could create a recursive static route where the router performs an additional lookup to find the exit interface. exit-intf Identifies the exit interface to forward packets. Creates a directly connected static route. Typically used in a point-to-point configuration. exit-intf ip-address Creates a fully specified static route because it specifies the exit interface and next-hop IPv4 address. distance Optional command that can be used to assign an administrative distance value between 1 and 255. Typically used to configure a floating static route by setting an administrative distance that is higher than a dynamically learned route.
Which two methods can be used to identify the next hop in a static route? (Choose two.)
next hop IP address, exit interface
In a next-hop static route, only the ___ is specified. The exit interface is derived from the ___.
next-hop IP address, next hop
It is recommended that when the exit interface is an Ethernet network, that the static route includes a ___. You can also use a fully specified static route that includes both the ___ and the ___.
next-hop address, exit interface, next-hop address
Three directly connected IPv4 static routes are configured on R1 using the exit interface. Using a ___ is generally recommended. Directly connected static routes should only be used with ___.
next-hop address, point-to-point serial interfaces
Three directly connected IPv6 static routes are configured on R1 using the exit interface. Using a ___ is generally recommended. Directly connected static routes should only be used with ___, as in this example.
next-hop address, point-to-point serial interfaces
A default route is used when ___. In other words, if a more specific match does not exist, then the default route is used as the ___
no other routes in the routing table match the destination IP address of the packet, Gateway of Last Resort.
An IPv4 default static route is commonly referred to as a ___
quad-zero route
Along with ___, ___, ___ and ___, other useful commands to verify static routes include the following:
show ip route, show ipv6 route, ping, traceroute show ip route static show ip route network show running-config | section ip route
The next hop must be directly connected to the ___. Using an ___ is optional, however it is necessary to use a ___.
specified exit interface, exit interface, next-hop address
A default route is a ___
static route that matches all packets
Floating static routes are ___. The floating static route is only used when the ___.
static routes that are used to provide a backup path to a primary static or dynamic route, in the event of a link failure, primary route is not available
A network administrator uses the command ip route 172.18.0.0 255.255.0.0 S0/0/1 to configure a floating static route on a router. That route will function as a backup route to reach the EIGRP learned network 172.18.0.0/16. After this configuration, the EIGRP route is removed from the routing table even though EIGRP is still functioning properly. Why is the static route not functioning as intended?
the administrative distance value is not high enough on the static route
Why would a floating static route be configured with an administrative distance that is higher than the administrative distance of a dynamic routing protocol that is running on the same router?
to be used as a backup route
A network administrator configures a router by the command ip route 0.0.0.0 0.0.0.0 209.165.200.226. What is the purpose of this command?
to provide a route to forward packets for which there is no route in the routing table
