[Bug 1731522] Re: systemd-resolved does not listen on TCP port, cannot serve large records (Cannot ping pod51041.outlook.com but can dig.)

[Daniel Richard G.]

Steve, Bionic still has the default (commented-out)

    #DNSStubListener=udp

in /etc/systemd/resolved.conf .

I've noticed that this breaks Kerberos KDC lookup at a large site,
because the reply is quite large:

    # host -t SRV _kerberos._udp.xxx.example.com
    ;; Connection to 127.0.0.53#53(127.0.0.53) for 
_kerberos._udp.xxx.example.com failed: connection refused.

    # kinit u...@xxx.example.com
    kinit: Cannot find KDC for realm "XXX.EXAMPLE.COM" while getting initial 
credentials

After setting DNSStubListener=yes:

    # host -t srv _kerberos._udp.xxx.example.com
    _kerberos._udp.xxx.example.com has SRV record 0 100 88 
xxxxxxx01.xxx.example.com.
    _kerberos._udp.xxx.example.com has SRV record 0 100 88 
xxxxxxx02.xxx.example.com.
    _kerberos._udp.xxx.example.com has SRV record 0 100 88 
xxxxxxx03.xxx.example.com.
    _kerberos._udp.xxx.example.com has SRV record 0 100 88 
xxxxxxx04.xxx.example.com.
    _kerberos._udp.xxx.example.com has SRV record 0 100 88 
xxxxxxx05.xxx.example.com.
    _kerberos._udp.xxx.example.com has SRV record 0 100 88 
xxxxxxx06.xxx.example.com.
    _kerberos._udp.xxx.example.com has SRV record 0 100 88 
xxxxxxx07.xxx.example.com.
    _kerberos._udp.xxx.example.com has SRV record 0 100 88 
xxxxxxx08.xxx.example.com.
    _kerberos._udp.xxx.example.com has SRV record 0 100 88 
xxxxxxx09.xxx.example.com.
    _kerberos._udp.xxx.example.com has SRV record 0 100 88 
xxxxxxx10.xxx.example.com.
    _kerberos._udp.xxx.example.com has SRV record 0 100 88 
xxxxxxx11.xxx.example.com.
    _kerberos._udp.xxx.example.com has SRV record 0 100 88 
xxxxxxx12.xxx.example.com.
    _kerberos._udp.xxx.example.com has SRV record 0 100 88 
xxxxxxx13.xxx.example.com.
    _kerberos._udp.xxx.example.com has SRV record 0 100 88 
xxxxxxx14.xxx.example.com.
    _kerberos._udp.xxx.example.com has SRV record 0 100 88 
xxxxxxx15.xxx.example.com.

    # kinit u...@xxx.example.com
    Password for u...@xxx.example.com:

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Title:
  systemd-resolved does not listen on TCP port, cannot serve large
  records (Cannot ping pod51041.outlook.com but can dig.)

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