Configuring Static Routing Flashcards
A router must perform what actions to route data?
Identify the destination of the packet: Determine the destination network address of the packet that needs to be routed by using the subnet mask.
Identify the sources of routing information: Determine from which sources a router can learn paths to network destinations.
Identify routes: Determine sources from which a router can learn paths to network destinations.
Select routes: Select the best path to the intended destination.
Maintain and verify routing information:Update known routes and the selected route according to network conditions.
What are the two ways routers can learn where to forward packets to destination networks that are not directly connected?
- You can enter destination network information manually, also known as a static route.
- Routers can learn destination network information dynamically through a routing protocol process that is running on the router.
What are the characteristics of static routes?
Static routes:
- A network administrator manually enters static routes into the router.
- A network topology change requires a manual update to the route.
- Routing behavior can be precisely controlled.
What are the characteristics of dynamic routes?
Dynamic routes:
- A network routing protocol automatically adjusts dynamic routes when the topology or traffic changes.
- Routers learn and maintain routes to the remote destinations by exchanging routing updates.
- Routers discover new networks or other changes in the topology by sharing routing table information.
When should you use static routes and when should you not?
Use static routes In these situations:
- In a small network that requires only simple routing
- In a hub-and-spoke network topology
- When you want to create a quick ad hoc route
- Common use is a default static route
Do not use static routes In these situations:
- In a large network
- When the network is expected to scale
What is the command to configure a static route to the next-hop IPv4 Address?
RouterA(config)# ip route 172.16.1.0 255.255.255.0 172.16.2.1
Destination network = 172.16.1.0 255.255.255.0
IPv4 of the next-hop router = 172.16.2.1
What is a host route and how is it configured?
A host route is a static route for a single host. A host route has a subnet mask of 255.255.255.255.
What is a floating static route and how is it configured?
A floating static route is a static route with administrative distance greater than 1.
RouterA(config)# ip route 172.16.1.0 255.255.255.0 172.16.2.1 10
What is a default static route and how do you configure one?
A default static route is a route that matches the destination address of all packets that don’t match any other more specific routes in the routing table.
RouterB(config)# ip route 0.0.0.0 0.0.0.0 172.16.2.2
OR
RouterB(config)# ip route 0.0.0.0 0.0.0.0 serial0/0/1
What is a default static route used for?
Default static routes are used in these instances:
- When no other routes in the routing table match the destination IP address of the packet or when a more specific match does not exist. A common use for a default static route is to connect the edge router of a company to an ISP network.
- When a router has only one other router to which it is connected. This condition is known as a stub router.
What is a quad-zero route?
The 0.0.0.0 network address and 0.0.0.0 subnet mask are called a quad-zero route.
For example: RouterB(config)# ip route 0.0.0.0 0.0.0.0 172.16.2.2
What is the command to verify static routes in the routing table?
show ip route
What is true of a routing table before static or dynamic routing can be used?
Routing tables must contain directly connected networks that are used to connect remote networks before static or dynamic routing can be used. This means that a route will not appear in the routing table of the router if the exit interface used for that specific route is disabled (administratively down) or does not have an IP address assigned. The interface state needs to be up/up.
When viewing the routing table on a Cisco router, what denotes that a route is a static route and what denotes that a route is the default route?
A static route is marked with the “S” code.
The asterisk (*) indicates that the route is a candidate default route.
What is the command to enable IPv6 routing on a Cisco router?
Router(config)# ipv6 unicast-routing
NOTE: If this command is not enabled, then locally connected routes still work, but the router will not route anything to other networks. (Learned this during the CBT Nuggets IPv6 Lab!)
