NodeLocalDNS send finish flag before get answer

[zvlb]

Sometimes i see strange error in NodeLocalDNS logs:

[ERROR] plugin/errors: 2 {{DOMAIN}}. SRV: read udp {{NODE_IP}}:51483->{{DNS_SERVER}}:53: i/o timeout

In TCPDump i see:

15:45:40.151621 IP {{NODE_IP}}.42761 > {{DNS_SERVER}}.domain: 51038+ SRV? {{DOMAIN}}. (50)
15:45:40.151777 IP {{DNS_SERVER}}.domain > {{NODE_IP}}.42761: 51038| 0/0/0 (50)
15:45:40.152005 IP {{NODE_IP}}.51483 > {{DNS_SERVER}}.domain: Flags [P.], seq 59:111, ack 1923, win 501, length 52 51038+ SRV? {{DOMAIN}}. (50)
15:45:40.152041 IP {{NODE_IP}}.51483 > {{DNS_SERVER}}.domain: Flags [F.], seq 111, ack 1923, win 501, length 0
15:45:40.152069 IP {{DNS_SERVER}}.domain > {{NODE_IP}}.51483: Flags [R], seq 1459978077, win 0, length 0

First 2 line - CoreDNS send UDP request for resolve domain, and DNS server answered: "Use TCP" 3 line - CoreDNS send TCP request for resolve domain 4 line - CoreDNS send F flag (finish connection) 5 line - DNS server answer with R flag, bc CoreDNS send F flag (RESET connection)

I can't understand why NodeLocalDNS send F flag, before DNS server answered on resolv request