CCNA routing interview questions test whether you can read a routing table, choose the correct path, and troubleshoot missing reachability. This guide covers static, default, and dynamic routing concepts.
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What is a routing table?
A routing table lists known destination prefixes, their sources, metrics, next hops, and outgoing interfaces.
How does longest prefix match work?
A router selects the matching route with the most specific prefix. A /24 route is preferred over a /16 route for an address matching both.
What is a static route?
A static route is entered manually and does not depend on a dynamic routing protocol. It provides predictable forwarding but requires administrative maintenance.
What is a default route?
A default route matches destinations that have no more-specific entry. In IPv4 it is represented by 0.0.0.0/0.
What is dynamic routing?
Dynamic routing protocols exchange reachability information and adapt to topology changes. Examples include OSPF and EIGRP.
What is administrative distance?
Administrative distance ranks the trustworthiness of route sources when they offer the same prefix. A lower value is preferred.
What is a routing metric?
A metric ranks paths learned by the same protocol. Depending on the protocol, it may use cost, bandwidth, delay, or hop count.
What is a floating static route?
It is a static route configured with a higher administrative distance than the primary route, allowing it to act as a backup.
Which command displays the routing table?
Use show ip route for IPv4 and show ipv6 route for IPv6. Protocol-specific commands provide additional detail.
How do you troubleshoot a missing route?
Verify interface state, addressing, the next hop, recursive lookup, protocol neighbors, advertised networks, filters, and the return path. Use ping and traceroute only after checking the control-plane information.