```
vyos@vyos# set interfaces dummy dum0 address 192.0.2.8/31
Invalid value
Value validation failed
Set failed
```
```
vyos@vyos# set interfaces dummy dum0 address 192.0.2.9/31
```
This happened to be an issue before (fixed in T1425, and reintroduced by fixing T2548)
The root cause is that `ipaddrcheck` is not properly aware of the /31 mask
```
$ ipaddrcheck --is-ipv4-host 192.0.2.9/31
$ echo $?
0
$ ipaddrcheck --is-ipv4-host 192.0.2.8/31
$ echo $?
1
```