There are different documents and books which are claiming that Administrative distance for static routes configured using exit interface is 1 and for the static route configured using next-hop IP address Administrative distance is 0.
R1(config)#ip route 20.0.0.0 255.255.255.0 10.10.2.1 R1(config)#ip route 20.0.0.0 255.255.255.0 fastEthernet 0/0
This is not true. Both of them are having AD value of 1. The confusion is coming from the info that directly connected interface has AD of 0, but static route outbound that interface is having the AD of 1.
Let’s make a simple lab for it. We add static route using both methods and have a look at the routing table. In last two lines we can see that there are both routes in the routing table one line for next-hop IP address and other line for exit interface. This confirms my thesis that both routes are having Administrative distance values 1. Only possible way to have two routes in routing table for the same destination is that they are having the same Administrative distance.
R1(config)#ip route 0.0.0.0 0.0.0.0 10.10.10.100
R1(config)#ip route 0.0.0.0 0.0.0.0 Serial0/0
R1(config)#sh ip route static
Codes: L - local, C - connected, S - static, R - RIP, M - mobile, B - BGP
D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
E1 - OSPF external type 1, E2 - OSPF external type 2
i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
ia - IS-IS inter area, * - candidate default, U - per-user static route
o - ODR, P - periodic downloaded static route, H - NHRP, l - LISP
+ - replicated route, % - next hop override
S 20.0.0.0/24 [1/0] via 10.10.10.100 (next-hop IP address)
is directly connected, Serial0/0 (exit interface)