Static, Default, & Summary Routes Flashcards
(8 cards)
What is the purpose of a floating static route? How do you ensure that a static route is treated as a floating static route?
To serve as a backup route that is only used if the primary route fails.
To configure a floating static route, set the route with a higher administrative distance than the primary route.
In this way, the static route “floats” and is not used when the route with the better administrative distance is active.
If the preferred route is lost, the floating static route can take over.
What are the different types of static routes?
Standard Static Route - To connect to a specific network.
Default Static Route - To provide a Gateway of Last Resort.
Floating Static Route - To provide a backup route in case a primary route link fails.
Summary Static Route - To reduce the number of routes advertised, by summarising several network routes as one static route.
What are the different types of standard static routes?
Next-Hop Static Route - Only the next-hop router’s IP address is specified.
- Every route that specifies only a next-hop router’s IP address and does not specify an exit interface must have the next-hop router’s IP address resolved using another route in the routing table with an exit interface.
Directly Connected Static Route - Only the router exit interface is specified.
- Directly connected static routes should only be used with point-to-point serial interfaces.
Fully Specified Static Route- Both the exit interface and next-hop router’s IP address are specified.
- Used when the exit interface connects to multiple devices (multi-access).
What is a recursive lookup?
When the router performs multiple lookups in the routing table before forwarding a packet, it is performing a process known as a recursive lookup.
A recursive lookup requires two routing table lookups.
What is a summary static route?
Route summarization is the process of summarizing a set of network addresses into a single network address with less-specific, shorter subnet mask.
What are the advantages of using a summary static route?
Reduces the size of routing tables on routers. This saves memory and results in faster routing table lookups.
Reduces the size of the routing updates (for dynamic routing protocols). This reduces bandwidth utilization for routing updates.
What is required for a summary static route to be established?
All the multiple static routes must use the same exit interface or next-hop router’s IP address.
The destination networks are contiguous (as much as possible) and can be summarized into a single network address.
Contiguous means that there are no gaps between the network addresses.
What are the steps to work out a summary static route?
Write out the network addresses to summarize in binary format.
Get the highest and lowest network addresses.
Count the number of far-left matching bits in the network addresses to determine the mask (or prefix length) for the summary route.
To find the summarized network address, copy the matching bits and add all 0 bits to the end to make 32 bits for an IPv4 summary route.
