networking - How to set static routes in Ubuntu Server
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The route itself is set by the user-space tools. There is no preference as any tool created for this reason will do. It can be either a DHCP client, ip command or route command. It is important to understand that NetworkManager changes the routing table whenever it creates a new connection.
About your current entries in your route table: First entry tell you the following: Any traffic with destination 10.0.0.0 will not be using a gateway (thats the * on the line), will be using a 255.255.255.0 net mask, route is UP (that's the meaning of the U) and which interface the route uses. Ubuntu Manpage: route - show / manipulate the IP routing table route del default deletes the current default route, which is labeled "default" or 0.0.0.0 in the destination field of the current routing table. route add default gw mango-gw adds a default route (which will be used if no other route matches). All packets using this route will be gatewayed through "mango-gw".