IP connectivity
⏱ ~3-min readAceMark Guide
What this topic is really about
HSRP (Hot Standby Router Protocol) is Cisco proprietary and provides a virtual default gateway shared by active and standby routers. VRRP is the open-standard equivalent, GLBP is also Cisco but adds load balancing, and STP prevents Layer 2 loops, not gateway redundancy.
An ABR sits between Area 0 (backbone) and one or more non-backbone areas and exchanges inter-area routes. Internal routers are entirely within one area, backbone routers are entirely within Area 0, and ASBRs connect OSPF to an external routing domain.
See the mechanism
ARP (Address Resolution Protocol) maps a known IPv4 address to its MAC. A diagram for this topic isn't available yet — the worked example below walks the same reasoning step by step.
An exam-style question, fully explained
What protocol does a router use to find the MAC address of a known IPv4 next-hop?
- Identify what the question tests: What protocol does a router use to find the MAC address of a known IPv4 next-hop.
- ARP (Address Resolution Protocol) maps a known IPv4 address to its MAC.
- DNS maps names to IPs, DHCP leases IPs to hosts, ICMP carries diagnostic messages like ping replies.
Traps the examiner sets
- Read each option carefully — distractors on IP connectivity are designed to look plausible.
- Re-check the exact wording of the question stem before committing to an answer.
- Watch the qualifiers ("always", "only", "except") that flip a correct-looking option.
Test your recall
Answer each from memory — you'll see instantly whether you're right and why.
Run a focused 10-question mini-mock on IP connectivity and see it stick.
Practice more of this topic →