Question : AD for iBGP and eGP routes.

AD for routes learned via iBGP are 200 and only 20 for eBGP.

There is a rule that iBGP peers do not advertise routes between themselves so if you get a route in the routing table with an AD of 200 does that mean that one of the routers has split-horizon turned off?

Why would you prefer  routes learned by eBGP over those learned by iBGP?

Answer : AD for iBGP and eGP routes.

--There is a rule that iBGP peers do not advertise routes between themselves so if you get a route in the routing table with an AD of 200 does that mean that one of the routers has split-horizon turned off?

You can not disable split horizon, it is always on no matter what.

--Why would you prefer routes learned by eBGP over those learned by iBGP?
http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a0080094431.shtml
I am assuming you mean step 7. no? I have not really thought about that before, it is good that you are asking questions like this one. You can look at it from this perspective, what is BGP used for? To exchange NLRI between ASes, correct? I believe that is the primary objective,so anything that is internal should be secondary and external ("e"BGP) should be primary, hence the lower AD (20).

Billy