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NTP Server via DHCP Server


i'm interested if it's possible to set the NTP server via DHCP on an 2901 Router with 15.2(2) image.

i configured the interface gigabit 0/0 as dhcp client. The DHCP Server sends to me DNS, Default GW and NTP. All is working fine, but the NTP will not be configured. i tried to add an DHCP option request, but there is no NTP (42) value

Router2901(config-if)#ip dhcp client request ?              

  classless-static-route       Classless static route (121)

  dns-nameserver               DNS nameserver (6)

  domain-name                  Domain name (15)

  netbios-nameserver           NETBIOS nameserver (44)

  router                       Default router option (3)

  sip-server-address           SIP server address (120)

  static-route                 Static route option (33)

  tftp-server-address          TFTP server address (150)

  vendor-identifying-specific  Vendor identifying specific info (125)

  vendor-specific              Vendor specific option (43)


is there any way to add the value NTP (42) for the DHCP request or isnt it possible?


5 Replies 5

Parvesh Paliwal
Level 3
Level 3

interesting thread

...answer from TAC

Problem Description:


NTP via DHCP request

Resolution Summary


Current IOS implementation doesn’t support option 42 in DHCP client.

Thanks Konrad,

At least you have responded back to the thread .... usually people just leave the thread open as it.



Old thread but I thought that I would respond to it. There's two formats that the IP address can be passed to the host. Hex format or ASCII format. I've run into IP phones (Aastra specifically) that are expecting the IP addresses to be passed to them using ASCII format. Here's examples:

option 42 ip <= hex format

option 42 ascii  ""  <= ascii format

What if we have normal windows hosts getting IP address via a DHCP server which i a router??

It looks like adding "option 42 ip " under dhcp pool doesn't help as my host is still with its own time set. In this case is the default gateway too for this subnet


ntp master


ip dhcp pool VLAN10



   option 42 ip



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