Maybe, maybe not: if your system "knows" time_server_name by name; i.e., you can open a terminal window and ping time_server_name
(obviously using the name of the server, not "time_server_name"), then, yes, you can use the name. It might be better, if the time server is using fixed IP addressing; i.e., the address of the server never changes, then if you use the actual address then the name doesn't have to be resolved. That means that your system does not have to contact a DNS server to get the address from the name (if you ping the server by name, the display will show you the address, for example)
prompt: ping -c 6 0.us.pool.ntp.org
PING 0.us.pool.ntp.org (22.214.171.124) 56(84) bytes of data.
64 bytes from 126.96.36.199: icmp_seq=1 ttl=49 time=213 ms
64 bytes from 188.8.131.52: icmp_seq=2 ttl=49 time=194 ms
64 bytes from 184.108.40.206: icmp_seq=3 ttl=49 time=252 ms
64 bytes from 220.127.116.11: icmp_seq=4 ttl=49 time=184 ms
64 bytes from 18.104.22.168: icmp_seq=5 ttl=49 time=252 ms
64 bytes from 22.214.171.124: icmp_seq=6 ttl=49 time=185 ms
--- 0.us.pool.ntp.org ping statistics ---
6 packets transmitted, 6 received, 0% packet loss, time 5003ms
rtt min/avg/max/mdev = 184.999/214.121/252.983/29.109 ms
The important thing is that your system can quickly and easily find the time server and you can use either the time server's name or the actual address (if it's fixed IP).
In the example I gave you, using a couple of pool servers in addition to your time server, I don't know their addresses and one of the truly nice things NTP does when you give it three or so time servers (the pool servers in this case) is that it will determine the best time server to use and switch from one to another if for some reason the initial choice drops out or becomes slower than one of the others. When you have an actual time server on your LAN, it's most likely going to be the closest electrically (that is the ping
time is the shortest) and NTP will synchronize with it all the time. The idea of having external pool servers available is that if you LAN time server goes away for some reason (system maintenance, the LAN goes down, the phase of the moon, whatever) there are one or two external servers to back it up just in case.
So, you can make your entry either way -- name or address. If you can ping the name, that'll work (and might be better if the server is not using fixed IP addressing). LAN time servers typically do not use DHCP addressing but, if yours does, then you want to use the server name because the address may change periodically.
And, once you've made your entries, stop NTPD then start NTPD. After about five minutes you can see if you're sync'd up by executing ntpq
prompt ntpq -p
remote refid st t when poll reach delay offset jitter
LOCAL(0) .LOCL. 10 l 58 64 177 0.000 0.000 0.001
+ntp1.Rescomp.Be 126.96.36.199 3 u 3 64 377 226.953 -6.159 3.536
*mirror 188.8.131.52 2 u 59 64 177 170.957 -5.269 7.542
+ns1.your-site.c 10.1.11.62 3 u 62 64 177 191.950 -3.331 7.818
Recall that I use three pool time servers (and this particular machine is on a dial-up line right now so the values are a little larger than they would otherwise be); the important thing is the plus signs and asterisk at the left end of the lines -- those tell you that you're in sync with the time server and that there are additional candidates for switching if the time server goes away.
Hope this helps some.