Chapter 5 - Routing and Advanced Switching

Which device is typically used to segment a broadcast domain?

Router - Routers do not forward broadcasts, so each router interface is its own broadcast domain. VLANs also segment broadcast domains on switches.

What is another name for the default route?

Gateway of last resort - The default route (0.0.0.0/0) is used when no more specific match exists in the routing table.

A host route for a single IPv4 device uses which prefix length?

/32 - A /32 matches exactly one IPv4 address. The IPv6 equivalent is /128.

Which command displays the routing table on a Windows host?

netstat -r - On Windows, netstat -r or route print shows the routing table. show ip route is the Cisco command.

A router learns the same destination from RIP, OSPF, and EIGRP. Which route is installed?

EIGRP (90) - The route with the lowest administrative distance wins: EIGRP is 90, OSPF 110, and RIP 120.

Which route has the lowest administrative distance, and therefore the highest trust?

Directly connected route - Directly connected is 0, static is 1, BGP is 20, EIGRP is 90, OSPF is 110, RIP is 120.

What is the metric used by RIP, and what is the maximum usable value?

Hop count, 15 - RIP uses hop count. 15 is the maximum, and 16 is considered unreachable.

Which statement describes OSPF?

Link-state protocol using cost and IP protocol 89 - OSPF routers share full topology information (link state) and use cost as the metric. It runs directly over IP protocol 89.

Which routing protocol connects different autonomous systems and runs the internet?

BGP - BGP is an exterior gateway protocol that exchanges routes between autonomous systems.

When multiple routes match a destination, which rule is applied first?

Longest prefix match - Longest prefix match is first, then lowest administrative distance, then lowest metric.

What does PAT (Port Address Translation) do?

Maps many private IPs to a single public IP using different port numbers - PAT, also called NAT overload, tracks sessions using ports so many internal hosts can share one public address.

Which type of NAT provides a one-to-one mapping between a private and a public address, useful for servers that need consistent external access?

Static NAT - Static NAT permanently maps one internal address to one public address.

What distinguishes a stateful inspection firewall from a basic packet filter?

It tracks the state of connections and decides based on traffic context - Stateful firewalls remember established sessions and allow return traffic automatically. Packet filters evaluate each packet alone by address, port, and protocol.

In the three-tier model, which layer typically uses Layer 3 switches to implement policy and provide fault-tolerant interconnection?

Distribution - The distribution layer aggregates access switches, performs inter-VLAN routing, and applies traffic policies.

What is the purpose of the native VLAN on a trunk?

It carries untagged traffic - Frames in the native VLAN are sent without an 802.1Q tag across the trunk. Both ends must agree on the native VLAN.

Which standard adds a VLAN tag to Ethernet frames on trunk links?

802.1Q - IEEE 802.1Q inserts a tag containing the VLAN ID. 802.1X is port authentication and 802.3af is PoE.

What does a Switch Virtual Interface (SVI) provide?

A Layer 3 interface on a switch that acts as the default gateway for a VLAN - An SVI (such as interface VLAN16) is a virtual Layer 3 interface that routes between VLANs on a Layer 3 switch.

What does split horizon do?

Prevents a routing update from being advertised back out the interface it was learned on - Split horizon helps prevent routing loops in distance-vector protocols. Other tools include holddown timers, route poisoning, and a maximum hop count.

Which layer of the three-tier model provides high-speed transport and does not connect end devices directly?

Core - The core is a high-speed backbone with redundant paths. End devices connect at the access layer.

Which design combines the core and distribution layers for medium-sized networks

Collapsed core - A collapsed core is a two-tier design that saves cost by merging two layers.

Which metrics does EIGRP use in its composite metric?

Bandwidth and delay - EIGRP uses bandwidth and delay by default. RIP uses hop count and OSPF uses cost.

Which VLAN is dedicated to VoIP traffic for better call quality?

Voice VLAN - A voice VLAN separates phone traffic from data. A guest VLAN isolates untrusted devices

What does the router-on-a-stick method use to route between VLANs?

Subinterfaces with 802.1Q encapsulation on one physical port - Each subinterface is assigned a VLAN ID and an IP address, and the router port connects to a trunk.

A traceroute shows the same two router IP addresses repeating. What is the likely problem?

Routing loop - Repeated hops mean packets are bouncing between routers. Check routing tables and loop-prevention settings.