TCP/UDP's OSI layer and routing AppleTalk

jeff CQ

I just took the practice exam for the Network+ and the first question asks:

1. On which layer of the OSI model do the TCP and UDP protocols reside?

a. Network
b. Transport
c. Data Link
d. Session

The actual correct answer should be b & c, right?
Let me know.

[EDIT: I've changed the title of this post to make it more descriptive and to prevent people getting the wrong impression about our practice questions. Webmaster]

Webmaster

www.techexams.net/technotes/networkplus/osimodel.shtml

www.techexams.net/technotes/networkplus/tcpipsuite.shtml

bellboy

they only reside on the transport layer

jeff CQ

I didn't mean to imply that you were wrong and I was right, I'm just confused because on one of the CBTs I have, Mike Meyers says that TCP & UDP work on both the transport and session layers.

Also, question number 33 asks:

33. Which of the following is not a routable protocol?

a. TCP/IP
b. IPX/SPX
c. AppleTalk
d. NETBEUI

The answer is d, but I don't think AppleTalk is routable.

Again, I'm not saying I'm right and you are wrong, just trying to clear things up with some explainations from the experts.

Webmaster

Now it's session?

but I don't think AppleTalk is routable

I don't want to sound rude or anything, but stop thinking... instead try to do some research first...
AppleTalk is VERY routable:
www.techexams.net/technotes/networkplus/appletalk.shtml

jeff CQ

haha, now I'm typing typos about typos.

I MEANT to put b & d in the original post. Sorry about that. I guess Mr. Meyers isn't as bright as he appears to be, because that's pretty much all I'm basing the AppleTalk question on. I sure am glad I found this site before I go take my test!

THANKS!

Webmaster

Well, that's the idea of the practice exams, to make you think about stuff (and doubt it if you like), but when it comes to it, it is only facts that matter in IT, not opinions... ...I can't believe Meyer's opinion is that AppleTalk is not routable. I was once a very popular protocol, which Cisco itself used in their corporate network, also still virtually every Cisco device supports it... especially the routers I'm sure Meyer knows of this fact. As well as that TCP is a Transport layer protocol, this is very basic info.

I'm not saying I never make mistakes, but you can trust I do a whole lot of back ground checking to verify the things I think I know before I put it online.

Nevertheless, I'm glad you found this site too

bellboy

is localtalk routable? maybe he meant that.

Webmaster

LocalTalk is a Data Link (Layer 2) and Physical (layer 1) specification, it defines a type of cabling and signalling, media access method, etc., that would be like asking if Ethernet is routable. "OSI-logically" nothing under the Network Layer can be routable, since to route data it has to be wrapped in a packet of a protocol on the Network layer (i.e. IP, IPX, AppleTalk's DDP) on it's way down the OSI layers. Also, there are (were ) routers that support (physical) LocalTalk connections, often in the form of a mini-din connector.

The only 2 non-routable LAN protocols I know of, are NETBEUI and LAT, both of them can still be found in some corporate networks.

AppleTalk is really not that bad when it comes to its capabilities, it just the large overhead produced by it's native routing protocols that doesn't make it very suitable for large internetworks.