Basic Router & Switch Setup Practice Questions

Answers and explanations appear when you work through the set above.

1. A Layer 2 switch has an IP address configured on VLAN 1 for management, but administrators on a different subnet cannot reach it. What else is typically required?

   • The switch needs ip routing enabled
   • Configure ip default-gateway
   • VLAN 1 must be deleted and recreated
   • The switch needs a loopback interface

2. PC1 and PC3 are in the same IPv4 subnet. Both switches start with empty MAC address tables, and PC1 has no ARP entry for PC3. When PC1 pings PC3 for the first time, what is the first frame PC1 sends?

   • An ICMP echo request destined directly for PC3
   • An ARP broadcast to discover PC3's MAC address
   • A DHCP discover message
   • A CDP neighbor announcement

3. Which command clears only the dynamically learned entries from a switch's MAC address table without removing statically configured entries?

   • clear mac address-table dynamic
   • clear arp-cache
   • mac address-table aging-time 0
   • clear mac address-table notification

4. A frame travels from a PC across a switch, through a router's Ethernet interface, over a serial WAN link using HDLC, and finally out another Ethernet interface to the destination PC. On the HDLC serial segment, what does the frame's Layer 2 header contain in place of MAC addresses?

   • The router's own loopback MAC address on both sides
   • No MAC addresses, HDLC uses point-to-point addressing
   • The destination PC's MAC address only
   • A broadcast MAC address of all Fs

5. In a path with no NAT or tunneling, an IPv4 packet crosses multiple routers and Ethernet segments. What happens to the Ethernet destination MAC address at each routed hop?

   • It stays exactly the same for the entire journey, since MAC addresses do not change hop to hop
   • Each hop rewrites it for the next device; the destination IP stays unchanged
   • It is replaced with the source PC's own MAC address at every hop
   • It is removed entirely once the packet reaches the first router

6. Which command shows the current contents of a switch's dynamically learned MAC address table?

   • show mac address-table dynamic
   • show arp
   • show interfaces status
   • show cdp neighbors detail | include Device

7. Why do many designs place switch management traffic in a dedicated VLAN instead of leaving it in default VLAN 1?

   • VLAN 1 cannot carry IP-based management traffic between the switch and an administrator
   • It reduces exposure and simplifies management-plane policy
   • Cisco switches block management packets on VLAN 1 in hardware, even when an SVI is configured
   • VLAN 1 has a maximum of 10 connected devices

8. A new switch is powered on with completely default settings and no configuration applied. Can it forward frames between connected hosts on the same VLAN right away?

   • No, an IP address is needed for switching
   • Yes, Layer 2 MAC learning and forwarding work without IP
   • No, VTP must be configured first
   • Yes, but only if spanning tree is manually disabled

9. On a router-to-router serial link, what determines whether the interfaces use HDLC or PPP encapsulation?

   • The serial cable type selects the Layer 2 protocol, with DCE using HDLC and DTE using PPP
   • Configured serial encapsulation; both ends must match
   • The switches negotiate it at Layer 3 using the destination subnet
   • PPP requires Ethernet framing and cannot be configured on a serial WAN interface