Which three are major inhibitors of ADSL line quality? (multiple answer)

To eliminate the need for adjacent routers on broadcast networks to form n(n-1)/2 adjacencies, IS-IS defines a pseudonode or Designated Intermediate System, DIS. All router on the broadcast medium form an adjacency with the DIS. The Backup DIS is called:

When using IS-IS for IP routing, Dual IS-IS defined by RFC 1195, what is true? (multiple answer)

In DMT DSL transmission systems, what is the effect of turning off half of the available downstream carriers (tones)?

What is true concerning fastpath versus interleaved mode in DMT DSL service?

IDSL and SDSL use what line coding scheme?

What is not a valid service type between an 827 and a 6400?

A DSL subscriber says that his DSL modem is trained at the subscribed rates, 1024 kbps downstream and 256 kbps upstream, but he has no access to the internet. The internet service was working until today. The modem remains trained – it is not dropping train or frequently retraining. Manually retraining the modem does not correct the problem. The customer can ping from his PC to the Ethernet interface on the DSL modem, but not addresses “in the network”. Initial troubleshooting shows that the DSL modem can ping the subscriber’s PC, but no addresses in the network. What could cause this problem?

What ADSL DMT line rate requires (occupies) the most bandwidth on a telephone line?

A DSL subscriber reports that the CPE modem untrains and retrains several times each hour, but not at regular intervals. The subscriber has a DMT modem operating on 10 kft of #26 cable (3 km of 0.4 mm cable). The provisioned downstream rate is 2 mbps, and the provisioned upstream rate is 256 kbps. When the modem retrains, the downstream DSL may be as low as 512 kbps. Sometimes manually retraining the modem allows it to return to a 2 mbps line rate, and sometimes manually retraining the modem does not improve the DSL line rate. Which options would cause the intermittent train/untrain symptom as described? (multiple answer)