Strange (unsecure?) route in Linux route table

[scubadude 2]

I use AirVPN on a Rapsberry PI (Raspbian Strech) and after I have started the AirVPN tunnel I look at the route table:

Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref Use Iface
0.0.0.0         10.21.124.1     128.0.0.0       UG    0      0   0   tun0
default         router.asus.com 0.0.0.0         UG    303    0   0   wlan0
10.21.124.0     0.0.0.0         255.255.255.0   U     0      0   0   tun0
137.227.232.109 router.asus.com 255.255.255.255 UGH   0      0   0   wlan0
128.0.0.0       10.21.124.1     128.0.0.0       UG    0      0   0   tun0
192.168.10.0    0.0.0.0         255.255.255.0   U     303    0   0   wlan0

An unnecessary entry (137.227.232.109) has been added. (router.asus.com is my wifi router).
The ip address is registered with US Department of the Interior at ARIN. While I live in the Netherlands.
A few days ago I saw a route entry, with an IP address registered in Vietnam.
 

After I stop AirVPN tunnel, this strange route entry is gone.

Has any of you ever seen anything like that?

[OpenSourcerer 1359]

A logfile might shed some light on whether this is something done by OpenVPN or its config file or not.

[scubadude 2]

Found it... :-)

 

It is the reverse DNS entry, which has been added to the route table.

I have never seen this before. And I don't know why the reverse DNS entry should be in de routing table ?

 

But the column is too small, so the line "5.107.208.21 .in-add.arpa" is shown as "5.107.208.21".

I looks like a regular IP address, which is not.