000-221 Question #92: Real Exam Question with Answer & Explanation

Question

Options

• AThe Ethernet cable from the system to the switch is disconnected or faulty.
• BThe Shared Ethernet Adapter in the Virtual I/O Server in the managed system has a problem and is
• CThe routing table has been flushed on the host and the default route is no longer configured.
• DDNS is disabled and the /etc/hosts file on the host does not contain the addresses for the hostnames

Explanation

Inability to ping any host by hostname - including LPARs on the same subnet reachable at the IP layer - points to a hostname resolution failure caused by disabled DNS and missing /etc/hosts entries.

Common mistakes.

• A. A disconnected or faulty physical Ethernet cable would also break IP-level connectivity, but LPARs sharing a virtual Ethernet adapter on the same VLAN within the same managed system communicate through the hypervisor's internal virtual switch without traversing the physical cable.
• B. A Shared Ethernet Adapter failure in the VIO Server would disrupt traffic between the internal virtual network and the external physical network, but intra-VLAN communication between LPARs on the same managed system does not traverse the SEA, so those LPARs would still be reachable by IP.
• C. A flushed routing table removes default and static routes needed to reach other subnets, but systems on the same local subnet are reached via direct layer-2 forwarding and do not require a routing table entry, so same-subnet LPARs would remain pingable by IP.

Concept tested. Hostname resolution via DNS and /etc/hosts in AIX

Reference. https://www.ibm.com/docs/en/aix/7.3?topic=management-configuring-hosts-file

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