What is Zooko's triangle?

Zooko's triangle is a trilemma of three properties that are generally considered desirable for names of participants in a network protocol:
  • Human-meaningful: Meaningful and memorable (low-entropy) names are provided to the users.
  • Secure: The amount of damage a malicious entity can inflict on the system should be as low as possible.
  • Decentralized: Names correctly resolve to their respective entities without the use of a central authority or service.
Source: Wikipedia

Which creteria does the DNS in I2P fulfill?

For this, one should clarify which aspect of the DNS one is looking at more closely in I2P.
Local addressbook: Once there is a local address book. The domain names with the corresponding destinations are stored in this. Once this model is looked at without further configuration.
DNS: Depending on the configuration, the domain names with the corresponding destinations are taken from several registries. This means that you always have an up-to-date list of domains, but also that name collisions can occur. For example, registrar A can have a different destination for a domain than registrar B. This configuration is considered under the generic term "DNS".
b32: And once there is like in Tor with .onion addresses in I2P .b32.i2p addresses. These are derived from a public key. As far as cryptography is secure (assumed here), no two .b32.i2p addresses can exist with different destinations.

Local addressbook

Human-meaningful: Names are stored in the address book in a way that is comprehensible to the user. These are freely selectable.
Secure: In the local address book, each domain name can have only one destination. Name collision is thus excluded.
Decentralized: The local address book is stored on the user's computer. It is therefore central.

DNS

Human-meaningful: Unless a domain with the same name is registered, the domain names are freely selectable at the registries. Therefore, it is also possible to choose human-meaningful names.
Secure: Depending on how far the registries "exchange" and depending on the configuration of the user it is possible that name collision occurs. Thus, a domain can have two or more destinations.
Decentralized: Anyone can open and operate a registry. (There is also no master implementation) There are currently several. The registries are not under the control of a central authority.

b32

Human-meaningful: The .b32.i2p addresses are derived from keys. These keys are created randomly. Therefore, the .b32.i2p addresses are also random. Thus they also have no special meaning for humans.
Note: There are also brute-force generated keys, which are partially human-meaningful. It is possible to generate new keys until a part of the key is human-meaningful. However, this is very laborious. Furthermore, it is almost impossible to create a whole .b32.i2p which is human-understandable. Even with some effort only the first characters of the .b32.i2p are human-meaningful.

Secure: Since .b32.i2p addresses are derived from cryptographic keys, it is virtually impossible to generate two identical .b32.i2p addresses with different destinations.
Decentralized: Anyone can generate new keys. A simple computer program is sufficient for this. It is therefore not possible for a central authority to have control over key generation.