flush cached host_name on IP change
description (somehow) implies that the host_name field is reset on IP change:
Host name as found in a reverse DNS lookup of the relay IP address. This field is updated at most once in 12 hours, unless the relay IP address changes. Omitted if the relay IP address was not looked up or if no lookup request was successful yet.
this would make sense but that does not seem to be the case:
+-----------------+-----------------+
| IP | host_name |
+-----------------+-----------------+
| 162.218.239.125 | 162.218.233.43 |
| 160.166.216.122 | 160.163.106.82 |
| 198.96.94.98 | 155.94.246.179 |
| 198.96.94.122 | 155.94.246.178 |
| 197.242.119.107 | 154.118.35.110 |
| 151.20.142.35 | 151.64.24.192 |
| 151.45.92.96 | 151.45.211.193 |
| 178.33.156.144 | 149.202.233.205 |
| 129.21.101.45 | 129.21.102.240 |
| 117.254.79.156 | 117.252.95.186 |
| 104.192.0.18 | 104.192.0.22 |
| 103.44.149.45 | 103.44.149.43 |
Additionally: I would suggest to omit the host_name record if IP == host_name (saves space).