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
   • A default gateway must be configured with 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 request broadcast, since PC1 does not yet know 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
   • no mac address-table
   • clear mac address-table all

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 at all, since HDLC is a point-to-point protocol that does not use MAC 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
   • It is rewritten at each hop to the MAC address of the next device on that segment, while the destination IP address in the packet stays the same
   • 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

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 traffic at all
   • Separating management from the default access VLAN reduces accidental exposure and makes management-plane policy easier to apply
   • Cisco switches physically block traffic on VLAN 1
   • 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, a switch must have an IP address configured before it can forward any traffic
   • Yes, Layer 2 switching of frames between hosts works out of the box without any IP configuration, since it only requires MAC learning and forwarding
   • 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 Layer 2 encapsulation is fixed by the cable type used
   • It is set with the encapsulation command on each serial interface, and both ends must match for the link to come up
   • It is negotiated automatically and cannot be manually configured
   • PPP is only used on Ethernet, never on serial links