Sometimes with category-rated unshielded twisted-pair or coax copper cabling, we get so absorbed in the testing of high-frequency specifications, such as attenuation and crosstalk, that we forget that it will never work unless each wire is properly connected to the right pins. Let’s see how well you understand simple connection testing or wiremapping UTP cables, and how much you know about troubleshooting problems. Correct answers and explanations are in red.
1. The UTP wiremap test checks _________.
A. Correct pinout of jacks and/or punchdowns
B. Correct cable manufacture
C. Attenuation at less than 10 MHz
D. Quality of IDC contact resistance
Wiremap only tests UTP cable for connections, certification testers test for high frequency performance per industry standards and verifiers test for proper network transmission.
2. Some UTP wiremappers that only test continuity cannot detect _________.
A. Crossed pairs
B. Transposed pairs
C. Split pairs
Testing split pairs requires testing at higher frequency because the DC wiremap looks OK.
3. Cable certification testers _________.
A. Test the wiremap first
B. Assume you already tested the wiremap
C. Ignore wiremap errors and test at high speeds
D. Test for T568A or T568B
Certification testers test wiremap first to make sure connections are correct before they test for performance.
4. UTP wiremaps are different when all terminations are T568A instead of T568B.
T568A and T568B connections have pairs 2 and 3 reversed but as long as the termination are the same on both ends, the wiremap will be the same.
5. A cable with T568A termination on one end of a link and T568B on the other will have a _________ error.
A. Crossed pairs
B. Reversed pair
C. Split pair
T568A and T568B connections have pairs 2 and 3 reversed so mixing them up causes crossed pairs.
6. A patchcord with T568A pinout on one end and T568B at the other end is used to connect two PCs and is called a _________ cable.
Ethernet systems allow two computers to be directly connected without a hub or switch using a crossover cable.
7. Terminating a T568B jack with the same color codes as a punchdown block or vice versa causes what error?
A. Split pairs on pairs 1 and 3
B. Split pairs on pairs 1 and 2
C. Split pair on pair 1
D. No errors
Jacks and punchdowns have different color codes that must not be mixed up because it will result in split pairs.
8. A UTP pair tested “open” means _________.
A. Two pairs were not connected properly
B. One or both wires on one pair are not terminated
C. Two pairs were crossed
D. The cable is broken
If either or both wires of the pair are not connected properly, the tester will call that pair open.
9. A reversed pair is caused when the _________?
A. Tip and ring are swapped
B. Solid and striped wires of the same color are reversed
C. Both of the above; they mean the same thing
D. Neither of the above
Tip is always the wire with the stripe and ring the solid wire.
10. All that coax cable generally requires is a simple continuity test to ensure the connector makes good contact with the shield of the cable.
Continuity on coax generally means the cable will perform well. Testing frequency performance requires expensive, complicated test equipment.
HAYES is a VDV writer and educator and the president of The Fiber Optic Association. Find him at www.jimhayes.com.