ntpq -p 결과 중 reach 의미

http://www.eecis.udel.edu/~ntp/ntpfaq/NTP-s-trouble.htm#Q-MON-REACH

What does 257 mean as value for reach?

(Inspired by Martin Burnicki)

The value displayed in column reach is octal, and it represents the reachability register. One digit in the range of 0 to 7 represents three bits. The initial value of that register is 0, and after every poll that register is shifted left by one position. If the corresponding time source sent a valid response, the rightmost bit is set.

During a normal startup the registers values are these: 0, 1, 3, 7, 17, 37, 77, 177, 377

Thus 257 in the dual system is 10101111, saying that two valid responses were not received during the last eight polls. However, the last four polls worked fine.

흠... 최근 8번의 시도의 결과인 듯... 1,3,5,7번째 시도가 성공했다면 01010101 따라서 8진수로는 125

어쨌든 377이 완벽한 정상이고 0 이 비정상...