Which of the following route types has 110 as default Administrative Distance (AD)?

(A) IGRP
(B) OSPF
(C) RIP
(D) IS-IS

OSPF is the correct answer.

Administrative distance is the feature that routers use in order to select the best path when there are at least two different routes to the same destination from two different routing protocols. Administrative distance defines the reliability of a routing protocol. Each routing protocol is prioritized in order of most to least reliable (believable) with the help of an administrative distance value.

The default Administrative Distances (AD) from the given route types are:

Route type	Administrative
Connected	0
Static	1
BGP (external routes [eBGP])	20
EIGRP (internal routes)	90
IGRP	100
OSPF	110
IS-IS	115
RIP	120
EIGRP (external routes)	170
BGP (internal routes [iBGP])	200
DHCP default route	254
Unusable	250