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Hi Uyota, STUB only allows LSA 1, 2, 3. Totally STUBBY only allows LSA 1, 2 and ABR will inject default route to STUB routers. You have to use any of them if your area is the last resort OSPF area and there are no more areas behind it.
NSSA only allows LSA 1, 2, 3, 7. NSSA Totally STUBBY allows LSA 1, 2, 7 and ABR will inject default route to NSSA routers. You have to use any of them if your area is a connected area to other AS or to other IGP routing protocol like RIP V2 or EIGRP and you need to stop LSA 5 and inject it as LSA 7 inside your OSPF domain.
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—–Original Message—– From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of Uyota Oyearone Sent: Monday, May 12, 2008 10:19 PM To: Cisco certification Subject: ospf stub & NSSA
Hi guys,

I am not 100% comfortable distinguishing btw. when to use nssa or stub

Assuming R1 connection to the rest of the ospf domain is through R3. Since R1 does not need specific routing information to the rest of the network, it just needs to receive only a default route.

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These two solutions seems to be doing the same thing for me
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*Solution 1*

R3#
router ospf 1
area 5 nssa no-summary

R1#
area 5 nssa.

*Sol.2*

R3#
area 5 stub no-summary

R1#
area 5 stub

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My question is when can you categorically use nssa over stub, or vice-versa?

Thanks

Uyota