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Destination host unknown 8: Source host isolated 9: Network administratively prohibited 10: Host administratively prohibited 11: Network unreachable for ToS: 12: Host unreachable for ToS: 13: Communication administratively prohibited 14: Host Precedence Violation 15: Precedence cutoff in effect 4 – Source Quench 0: deprecated [10] Source ...
Ping measures the round-trip time for messages sent from the originating host to a destination computer that are echoed back to the source. The name comes from active sonar terminology that sends a pulse of sound and listens for the echo to detect objects under water. [1] Ping operates by means of Internet Control Message Protocol (ICMP) packets.
The address a host assigns to itself when address request via DHCP has failed, provided the host's IP stack supports this. This usage has been replaced with the APIPA mechanism in modern operating systems. A way to explicitly specify that the target is unavailable. [7] A way to route a request to a nonexistent target instead of the original target.
ICMPv6 provides a minimal level of message integrity verification by the inclusion of a 16-bit checksum in its header. The checksum is calculated starting with a pseudo-header of IPv6 header fields according to the IPv6 standard, [6] which consists of the source and destination addresses, the packet length and the next header field, the latter of which is set to the value 58.
The network with the longest subnet mask or network prefix that matches the destination IP address is the next-hop network gateway. The process repeats until a packet is delivered to the destination host, or earlier along the route, when a router has no default route available and cannot route the packet otherwise.
Cisco's implementation of traceroute also uses a sequence of UDP datagrams, each with incrementing TTL values, to an invalid port number at the remote host; by default, UDP port 33434 is used. An extended version of this command (known as the extended traceroute command) can change the destination port number used by the UDP probe messages. [13]
When you get a message from a "MAILER-DAEMON" or a "Mail Delivery Subsystem" with a subject similar to "Failed Delivery," this means that an email you sent was undeliverable and has been bounced back to you.
This is a list of the IP protocol numbers found in the field Protocol of the IPv4 header and the Next Header field of the IPv6 header.It is an identifier for the encapsulated protocol and determines the layout of the data that immediately follows the header.