TESTED ANSWERS GRADED A+
● What is the Julian Calendar?. Answer: - Created by Julius Caesar in 46
BC
- 365 days in year
- Error in leap year calculation
● What is the Gregorian Calendar?. Answer: - Decreed by Pope Gregory
XIII on Feb 24, 1582
- Still had 365 days in a year
- Fixed leap year calculation
● What happened in September of 1752?. Answer: - Great Britain and
colonies changed from Julian to Gregorian calendar
- in order to adjust for leap year calculation, skipped last 11 days of the
month (making it a 19 day month)
● How is time represented in UNIX systems? Windows?. Answer:
UNIX: system clock is UTC, 13:00 -5 DST, keeps time based on
seconds since UNIX Epoch, 00:00:00 January 1, 1970 (overflows
January 19, 2038 if not fixed)
,Windows: system clock is local time zone, 9:00 AM -5 +1
● What are the two types of computer clocks? Differences?. Answer:
Real Time Clock - keeps time in BIOS
System time - kept by process running in OS, depends on constant
processor clock speeds
● How is time synchronized in Windows non-domain systems? Domain-
based systems?. Answer: Non-domain: no built in synchronization,
default is to sync to time.windows.com via SNTP
Domain: Primary Domain Controller is time server, all domain members
synchronize to PDC
● What is SNTP?. Answer: Simple Network Time Protocol
● How many transactions can SNTP complete? What does this mean?.
Answer: - Single transactions
- Sets time once
- can be done repeatedly on a schedule - time can be off between syncs
● What is NTP?. Answer: Network Time Protocol
, ● How does NTP work?. Answer: - Uses UTC complete with leap
seconds
- keeps clock constantly correct
- requires client to adjust internal clock to match reference time
● What is Marzullo's algorithm?. Answer: used by NTP, takes into
account transmission duration for time data
● How is a machine's stratum level determined?. Answer: A machine is
one strata higher than the time server to which it synchronizes
● What are stratum 0 time sources?. Answer: Satellites, GPS receivers,
Atomic clocks
● What are stratum 1 time servers?. Answer: Machines directly
connected to stratum 0 time sources, used only to service other time
servers
● What are stratum 2 servers?. Answer: Reference at least two stratum 1
servers, typically only service stratum 3 servers
● What are stratum 3 servers?. Answer: Get time from multiple stratum
2 servers, typically serve clients within an organization, can serve higher
level time servers (up to 16 levels)