Hosts down , can ping them from the CLI

This support forum board is for support questions relating to Nagios XI, our flagship commercial network monitoring solution.
Post Reply
Posts: 21
Joined: Tue Apr 11, 2023 1:44 pm

Hosts down , can ping them from the CLI

Post by deby23456 »

Starting last night we have the vast majority of our hosts showing as down, all services are showing as up. I can ping the hosts from the cli. I have run the latest update and rebooted, no change. Where should i look next?

Check which plugin you're using to check hosts. I've noticed that check_ping sometimes doesn't work but check_icmp does.
Posts: 12
Joined: Tue Feb 04, 2020 3:40 pm

Re: Hosts down , can ping them from the CLI

Post by aiqbal88 »

it has to do with arp table
The Address Resolution Protocol (ARP) handles the mapping between an Internet Protocol (IP) address and a Media Access Control (MAC) address. Linux stores all such mappings in a local system cache called an ARP table.
Since it maps IP to MAC addresses, ARP works with IPv4 between layers 2 and 3 of the Open Systems Interconnection (OSI) model. Critically, the Network Discovery Protocol (NDP) replaces ARP for IPv6.

In addition to handling the mappings, ARP also allows the discovery of hosts on the network via requests. In fact, we can leverage ARP as a layer 2 ping via the arping command.

arpa -a

ping xx.xx.xx.xx

arpe -a
Post Reply