What is a route?

A route is a rule on a router that specifies where to send IP packets to reach a particular network.

Short and to the point: a route describes the path to a network: through which interface or next hop the packet should be sent.

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#What a route consists of

A typical route entry contains:

1. Destination network For example: 192.168.2.0/24 → which network the route belongs to
2. Next hop or outgoing interface

• the IP of the next router
• or the interface through which the packet should be sent

3. Metric (cost) (not always)

• used to choose the best route when there are several

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#Where routes are stored

All routes are kept in the router's (or OS's) routing table.

A router:

• looks at the packet's destination IP address
• searches for the most suitable route
• sends the packet according to the rule it found

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#Main types of routes

#1. Connected route

• the network is directly attached to the interface
• created automatically

#2. Static route

• configured manually by the administrator
• simple and predictable

#3. Dynamic route

• obtained through routing protocols
• updated automatically

#4. Default route

• used when there is no more specific match
• usually looks like:

0.0.0.0/0

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#Important points for an interview

• routes are defined for networks, not for individual IPs
• the most specific route is chosen (with the longest prefix)
• if there is no route:
  • the packet is dropped
  • or it is sent via the default route