Black hole (networking)
place in a network where incoming traffic is silently discarded without informing the source
In networking, a black hole or sinkhole is a place in the network where incoming or outgoing traffic is discarded or "dropped" without informing the source that the data did not reach its intended recipient.
When examining the topology of the network, the black holes themselves are invisible, and can only be detected by monitoring the lost traffic.
The name is presumed to have originated from the astronomical body (black hole) or the hydrological feature (sinkhole).
Addresses
A black hole IP address specifies a host machine that is not running or an address to which no host has been assigned.
Even though TCP/IP provides a means of communicating the delivery failure back to the sender via ICMP, traffic destined for such addresses is often just dropped.
Blackholed addresses are undetectable only to protocols that are both connectionless and unreliable (e.g., UDP). Connection-oriented or reliable protocols (TCP, RUDP) will either fail to connect to a blackholed address or will fail to receive expected acknowledgements.
For IPv6, the black hole prefix is 100::/64.
For IPv4, no black hole address is explicitly defined, however the reserved IP addresses can help achieve a similar effect. For example, 198.51.100.0/24 is reserved for use in documentation and examples; while the RFC advises that the addresses in this range are not routed, this is not a requirement.
This brief starts where responsible research should: with the source description of “Black hole (networking)” as place in a network where incoming traffic is silently discarded without informing the source. Everything that follows is an evidence route, not borrowed authority.
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The subject matters to the general reference register because the source frames it as place in a network where incoming traffic is silently discarded without informing the source. Its deeper value depends on whether names, dates, institutions and citations support that framing.
The citation trail is more important than the brevity of the summary: it shows where individual claims can be examined in context. The source revision retrieved here is dated Aug 26, 2026. The linked authority identifier is Q880302. None of the 0 selected statements returned an explicit reference.
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This entry incorporates text from “Black hole (networking)” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.