How are the values metric and administrative distance used in routing?
Metric is the measure used to decide which route is better (lower number is better). Each routing protocol uses its own metric. For example, RIP uses hop counts as a metric, while OSPF uses cost. The following example explains the way RIP calculates its metric and why it chooses one path over another.
For what purpose is an administrative distance ad used?
Administrative Distance (AD) is used to rate the trustworthiness of routing information received from the neighbor router. The route with the least AD will be selected as the best route to reach the destination remote network and that route will be placed in the routing table.
What is the value of administrative distance for the local host route?
Now look at the routing table. It shows that the RIP routes are preferred. They are learned with an administrative distance of 90, although the default is 120….Default Distance Value Table.
| Route Source | Default Distance Values |
|---|---|
| Intermediate System-to-Intermediate System (IS-IS) | 115 |
| Routing Information Protocol (RIP) | 120 |
What is the administrative distance of directly connected route?
Connected routes always take precedence over static or dynamically discovered routes because they have the administrative distance value of 0 (the lowest possible value).
What is the value of administrative distance?
Administrative Distance counts the reliability of a routing protocol. Administrative Distance (AD) is a numeric value which can range from 0 to 255. A smaller Administrative Distance (AD) is more trusted by a router, therefore the best Administrative Distance (AD) being 0 and the worst, 255.
What is the best possible value for administrative distance?
Administrative distance – Which route is the best?
| Protocol | Administrative distance |
|---|---|
| DHCP-learned | 254 |
| Internal BGP | 200 |
| External EIGRP | 170 |
| ODR | 160 |
What is administrative distance value?
From Wikipedia, the free encyclopedia. Administrative distance (AD) or route preference is a number of arbitrary unit assigned to dynamic routes, static routes and directly-connected routes. The value is used in routers to rank routes from most preferred (low AD value) to least preferred (high AD value).
What is the administrative distance of a static route?
1
Static routes have a default administrative distance of 1. A router prefers a static route to a dynamic route because the router considers a route with a low number to be the shortest.
What is the administrative distance of the route that will be installed in the routing table?
90
It shows that the RIP routes are preferred. They are learned with an administrative distance of 90, although the default is 120….Default Distance Value Table.
| Route Source | Default Distance Values |
|---|---|
| Routing Information Protocol (RIP) | 120 |
| Exterior Gateway Protocol (EGP) | 140 |
| On Demand Routing (ODR) | 160 |
| External EIGRP | 170 |
What does administrative distance mean?
Administrative distance refers to the trustworthiness of a particular route. A router first installs routes with higher administrative distances. Routes with the smallest metric to a destination indicate the best path.
What is the administrative distance of a route?
An administrative distance is a number between 0 and 255, with the lower number being better. The AD of 0 indicates the most trusted route (the directly connected network). The AD of 255 means that the route will not be trusted. Here are the default AD values for a different routing protocols: Connected interface – 0. Static route – 1. EIGRP – 90.
What is the difference between AD number and administrative distance?
The route learned using the routing protocol with a lower AD number will be placed in the routing table. An administrative distance is a number between 0 and 255, with the lower number being better. The AD of 0 indicates the most trusted route (the directly connected network).
How does a router select the route from the smallest administrative distance?
If a router learns a destination route from two or more routing protocols, it selects the route from the protocol having the smallest Administrative Distance. The table below shows the default AD values for each routing protocol:
What is administrative distance number in Cisco router?
Administrative distance number is used by routers to find out which route is better (lower number is better). For example, if the same route is learned from RIP and EIGRP, a Cisco router will choose the EIGRP route and stores it in the routing table.