This read-only counter tallies ICMP echo error responses that are not host-unreachable errors, covering other error types encountered during IP SLA operations. Admins use this to further categorize probe failures beyond simple host-unreachable conditions, helping narrow down the exact nature of a network fault. For example, a rising value here without a corresponding rise in the host-unreachable counter would point the admin toward a different class of network error, such as a network-unreachable response.