What are seednodes?



A follow up from a comment on this answer.

What are seednodes, and how do they differ from fallback nodes?


Posted 2012-05-17T20:36:03.133

Reputation: 42 235



"Fallback nodes" is a page on the Bitcoin Wiki which lists some reliable Bitcoin nodes. "DNS Seeds" are DNS servers hard-coded into Bitcoin which return IP addresses of Bitcoin nodes which can be used for bootstrapping. "Seednodes" are Bitcoin nodes which have their IP addresses hard-coded into the Bitcoin client (see list here); they're used as an alternative bootstrapping method.


Posted 2012-05-17T20:36:03.133

Reputation: 8 416

This link from your answer is (three years later) rotten. Fixed link (based on post date).

– Gustavo Rodrigues – 2015-04-10T19:55:56.900


DNS seeds aren't necessarily "seednodes" as they don't necessarily have have Bitcoin running as well. Instead these hosts have standard DNS servers with A records that new Bitcoin nodes use for bootstrapping to learn of peers.

Currently, Bitcoin master shows these four:

  • bitseed.xf2.org
  • dnsseed.bluematt.me
  • seed.bitcoin.sipa.be
  • dnsseed.bitcoin.dashjr.org

Source code:


// DNS seeds
// Each pair gives a source name and a seed name.

// The first name is used as information source for addrman.
// The second name should resolve to a list of seed addresses.

static const char *strMainNetDNSSeed[][2] = {
    {"bitcoin.sipa.be", "seed.bitcoin.sipa.be"},
    {"bluematt.me", "dnsseed.bluematt.me"},
    {"dashjr.org", "dnsseed.bitcoin.dashjr.org"},
    {"xf2.org", "bitseed.xf2.org"},
    {NULL, NULL}

Stephen Gornick

Posted 2012-05-17T20:36:03.133

Reputation: 26 454

Those are DNS seeds. Seednodes are different. – theymos – 2012-05-17T21:35:59.047