ping and traceroute: Best Tools to Test Host Connectivity

Direct reachability versus path evidence The stem’s key qualifiers are “verify reachability,” “after an outage,” and “test connectivity between hosts.” Those words point to tools that actively send probes and observe responses between endpoints. ping (A) is the direct ICMP echo-request/echo-reply test: it answers whether a host is reachable and gives round-trip time. traceroute (E) sends probes with increasing TTLs and reveals the hop-by-hop path, so it both tests connectivity and localizes where it breaks. Together they satisfy the two-answer requirement.

Why the other options do not fit the requirement LLDP (B) is a neighbor-discovery protocol for directly connected devices; it advertises identity and port information and does not test end-to-end host reachability. nslookup (C) queries DNS records—useful for name resolution, but a successful name lookup does not prove that a host is reachable. arp (D) resolves IPv4 addresses to MAC addresses on the local broadcast domain; it can confirm an entry exists, but it is not an end-to-end reachability test and cannot trace across routers. SNMP (F) polls management data from agents and can show interface status or statistics, but it is a monitoring protocol, not a host-to-host connectivity test.

Exam wording and answer selection Because the question asks for exactly two, the best pair is A and E. A single ping is the first check; traceroute adds path visibility when the outage may be caused by a routing or intermediate-hop failure. If only local-subnet reachability were asked, ARP might look tempting, but “between hosts on the network” after an outage implies IP-level connectivity, including routed paths. Therefore ping and traceroute are the tools that directly answer the stem, while B, C, D, and F answer different questions.