client.dns.lookup 选项中的“use_all_dns_ips”和“resolve_canonical_bootstrap_servers_only”之间的确切区别是什么？

Question

在kafka-client 2.1.0中，client.dns.lookup可用。以下是每个选项的说明。

1. use_all_dns_ips

   当查找返回主机名的多个 IP 地址时，在连接失败之前将尝试连接所有这些 IP 地址

2. 仅限resolve_canonical_bootstrap_servers_only

   每个条目都将被解析并扩展为规范名称列表

他们不是都使用dns吗？use_all_dns_ips和resolve_canonical_bootstrap_servers_only之间有什么区别？

Answer 1

虽然这两个选项都与 DNS 有关，但它们是不同的：

• use_all_dns_ips: When resolving broker hostnames, if multiple IPs are returned for a name, the client will store them all and cycle through all IPs if it gets disconnected.

  More details in the KIP: https://cwiki.apache.org/confluence/display/KAFKA/KIP-302+-+Enable+Kafka+clients+to+use+all+DNS+resolved+IP+addresses

• resolve_canonical_bootstrap_servers_only: When enabled, once a hostname has been resolved, the client is do a reverse lookup to find the FQDN. This can be required in some cases when using SASL GSSAPI.

  More details in the KIP: https://cwiki.apache.org/confluence/display/KAFKA/KIP-235%3A+Add+DNS+alias+support+for+secured+connection