I am preparing to take the CCNA exam and have been both hitting the books and searching wikipedia for some answers to some questions might be too basic to ask on serverfault, although I'm not sure.

I've spent more time than I'd like to admit trying to figure these out:

  • (for the CCNA) does "T1", "T3" mean anything besides a speed? The books seems to only refer to it in regards to WANs, so is a T1 connection ever used for anything besides WANs? Do all the different WAN protocols (e.g. Frame Relay, ISDN, PPP, Cable, DSL, MPLS) belong to one of these classes, T1-T5?
  • As I understand it, the reason we have a separate term "WAN" defined is because a "WAN" is physically different from a "LAN"; it spans a large distance, so it requires serial transimission protocols, (e.g. X.25) instead of Ethernet, is that correct? Is this why a Cisco router might have certain "interfaces" designated for FastEthernet connections and others for serial (WAN) connections?
  • When we're talking about controllers, DCEs, DTEs, DSUs are we talking about the data link layer or physical layer?
  • Why would WICs be necessary instead of a NIC?

Would any one of these questions be considered on-topic here? If these questions are not suitable for serverfault, where are they better directed? Cisco's community forums? Thanks for any help.


2 Answers 2


All of them are on-topic here. Feel free to ask them on the main site.

Side note: If you can find anyone in real life to help mentor you, you'll be miles ahead. I say this mostly because you've got a lot of misconceptions in those questions. And many of the details are going to be best articulated with an extended history lesson.

  • After crawling through some 2000 pages of the CCNA official cert guide, I can see some of that now. I don't know any real-life mentors. I'd like to ask what a network engineer does day-to-day, but that question got closed - next comment- Are there any sites where that question wouldn't be off-topic?
    – T. Webster
    Commented Mar 28, 2013 at 5:05
  • discuss.area51.stackexchange.com/questions/9817/…‌​ineer
    – T. Webster
    Commented Mar 28, 2013 at 5:06
  • Unfortunately the answer is 'no', the community decided career-type questions are off-topic on SF. You can drop by Server Fault Chat and ask, but I don't think we have many network engineers around (they're pretty scarce in the business world, usually only very large companies and consulting firms would have them). I would imagine they split their time like most other IT Admins: troubleshooting, upgrading, monitoring, reporting, with a small doses of planning/engineering and major upgrades.
    – Chris S
    Commented Mar 28, 2013 at 13:00

Yeah, these sites are best for specific, targeted, preferably real-world technical questions. If you want more general guidance, either for a project or on free-ranging discussions, LOPSA runs a mentoring program, if you don't have local contacts to work with.


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