Routing Commands
To view the IPv4 routing table on a Cisco IOS device, which command should an administrator enter?
show ip route
Which type of logical interface allows a multilayer switch to perform inter-VLAN routing?
A Switch Virtual Interface (SVI)
Where is the routing table, also called the Routing Information Base (RIB), stored on a router?
In RAM
What function do the IP addresses assigned to router sub-interfaces perform for hosts within each VLAN in a ROAS setup?
They serve as each VLAN subnet's default gateway
Which command converts a Layer 3 switch port from a switched port into a routed port?
no switchport
Why are Layer 3 switches much faster at inter-VLAN routing than the router-on-a-stick method?
They route traffic in hardware using Application-Specific Integrated Circuits (ASICs)
How is Administrative Distance (AD) best defined?
A number between 0 and 255 indicating the trustworthiness of a routing information source, with lower numbers being more reliable
A packet destined for 192.168.0.45 arrives at a router whose table contains both 192.168.0.0/16 and 192.168.0.0/24. Which entry wins the lookup?
The /24 entry, since the Longest Prefix Match rule prefers the route matching the greatest number of bits
Most multilayer switches operate only at Layer 2 out of the box. Which global command turns on their routing capability?
ip routing
What is the correct sequence for these route sources by default Administrative Distance, starting with the most trusted?
OSPF (110), Static Route (1), Connected Interface (0), eBGP (20)
Connected Interface (0), Static Route (1), eBGP (20), OSPF (110)
What does the "L" (Local) code indicate about an entry in a Cisco routing table?
The exact IP address assigned to a router interface, listed as a /32 host route
If a router receives routes to the identical prefix from OSPF and from a static configuration, which one gets installed in the routing table?
The static route, since its administrative distance of 1 beats OSPF's 110
What command shows only certain parts of the full "show run" command?
sh run | b [word you're looking for]
In a router-on-a-stick (ROAS) design, what does the single router interface connect to on the Layer 2 switch side?
An 802.1Q trunk port on a Layer 2 switch
In the two-plane model of modern routing, what plane builds the Routing Information Base (RIB) by learning about networks?
The control plane
What table, derived from the RIB, allows the data plane to forward packets at hardware speed?
The Forwarding Information Base (FIB)
When configuring a router sub-interface for router-on-a-stick, which command tags its traffic with VLAN 10?
encapsulation dot1Q 10
How large is the tag that the IEEE 802.1Q standard inserts into an Ethernet frame, and where is it placed?
A four-byte tag placed between the source MAC address and the EtherType/Length field
Given the route entry "O 192.168.0.0/24 [110/10] via 172.16.0.1, 00:00:25, GigabitEthernet0/0/0", what information does the value 10 inside the brackets convey?
The metric, meaning the protocol-specific cost of reaching the destination
What is the primary performance limitation of the router-on-a-stick method?
All inter-VLAN traffic crosses the same physical link twice, effectively cutting its useful bandwidth in half