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Net Unreachable |
The sending device knows about the network but believes it is not available at this time. Perhaps the network is too far away through the known route. |
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Host Unreachable |
The sending devices knows about host but doesn’t get ARP reply, indicating the host is not available at this time |
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Protocol Unreachable |
The protocol defined in IP header cannot be forwarded. |
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Port Unreachable |
The sending device does not support the port number you are trying to reach |
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Fragmentation Needed and Don’t Fragment was Set |
The router needs to fragment the packet to forward it across a link that supports a smaller maximum transmission unit (MTU ) size. However, application set the Don’t Fragment bit. |
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Source Route Failed |
ICMP sender can’t use the strict or loose source routing path specified in the original packet. |
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Destination Network Unknown |
ICMP sender does not have a route entry for the destination network, indicating this network may never have been an available. |
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Destination Host Unknown |
ICMP sender does not have a host entry, indicating the host may never have been available on connected network. |
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Source Host Isolated |
ICMP sender (router) has been configured to not forward packets from source (the old electronic pink slip). |
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Communication with Destination Network is Administratively Prohibited |
ICMP sender (router) has been configured to block access to the desired destination network. |
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Communication with Destination Host is Administratively Prohibited |
ICMP sender (router) has been configured to block access to the desired destination host. |
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Destination Network Unreachable for Type of Service |
The sender is using a Type of Service (TOS) that is not available through this router for that specific network. |
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Destination Host Unreachable for Type of Service |
The sender is using a Type of Service (TOS) that is not available through this router for that specific host. |
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Communication Administratively Prohibited |
ICMP sender is not available for communications at this time. |
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Host Precedence Violation |
Precedence value defined in sender’s original IP header is not allowed (for example, using Flash Override precedence). |