NetworkManagerやらresolvconfやらLinuxのDNSまわりを調べて、DHCP環境下でDNSキャッシュしてみた ref: https://qiita.com/onokatio/items/af0035d1563acbbfeed2

file0.txt

$ sudo apt install pdnsd # Debian、Ubuntuの場合
$ sudo pacman -S pdnsd   # ArchLinuxの場合

file3.txt

$ sudo systemctl start pdnsd
$ sudo systemctl enable pdnsd #自動起動

pdnsd.conf

global {
        perm_cache=1024;
        cache_dir="/var/cache/pdnsd";
#       pid_file = /var/run/pdnsd.pid;
        run_as="pdnsd";
        server_ip = 127.0.0.1;  # Use eth0 here if you want to allow other
                                # machines on your network to query pdnsd.
        status_ctl = on;
#       paranoid=on;       # This option reduces the chance of cache poisoning
                           # but may make pdnsd less efficient, unfortunately.
        query_method=udp_tcp;
        min_ttl=15m;       # Retain cached entries at least 15 minutes.
        max_ttl=1w;        # One week.
        timeout=10;        # Global timeout option (10 seconds).
        neg_domain_pol=on;
        udpbufsize=1024;   # Upper limit on the size of UDP messages.
}

server {
    label=resolvconf;
    file=/etc/pdnsd-resolv.conf;
    proxy_only=on;
    timeout=4;
    uptest=if;
    interface=wlp1s0;
    interval=10;
    purge_cache=off;
#   edns_query=yes;
    preset=off;
}

resolvconf.conf

# Configuration for resolvconf(8)
# See resolvconf.conf(5) for details

resolv_conf=/etc/resolv.conf
# If you run a local name server, you should uncomment the below line and
# configure your subscribers configuration files below.
name_servers=127.0.0.1
name_servers_append=8.8.8.8
pdnsd_resolv=/etc/pdnsd-resolv.conf