What are the conditions for RouterOS to cache a DNS record?

RouterOS General
1

It looks like RouterOS does not always cache a DNS response with respect to its TTL. E.g. attempts to resolve pool.ntp.org never end up adding the record to /ip dns cache. Is it because TTL is too short or because RouterOS can recognize the round robin DNS?

2

Can’t confirm:

[sob@CHR4] > :resolve pool.ntp.org; /ip/dns/cache/print 
Columns: NAME, TYPE, DATA, TTL
# NAME          TYPE  DATA             TTL  
0 pool.ntp.org  A     81.2.248.189     2m30s
1 pool.ntp.org  A     147.251.48.140   2m30s
2 pool.ntp.org  A     78.108.96.197    2m30s
3 pool.ntp.org  A     162.159.200.123  2m30s

And they stay in cache for next two and half minutes, as TTL allows.

3

Indeed. Further testing it I noticed that by default my nslookup used the IPv6 address and not of my router but of my ISP (I have stateless IPv6 without DHCPv6).