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NIOS DNS DHCP IPAM

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Some routers returns DHCP NAK

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I did a DHCP client which work with about 70% of DHCP servers. But some of routers(DHCP servers) have a problem and send NAK for DHCP Reequest. Im not able found what ever do for rest of servers. What is bad or which parameter missing in Request packet.
I tried change some option, controll checksums etc. but no mistake found. 

Zyxel router wrote in log:

2019 -05 -09 T14:58:40 daemon notice syslog: Receive DHCP DISCOVER from 00:4F:49:0D:FF:FF 99

2019 -05 -09 T14:58:40 daemon notice syslog: Send DHCP OFFER to 00:4F:49:0D:FF:FF with IP 99

2019 -05 -09 T14:58:40 daemon notice syslog: Receive DHCP REQUEST from 00:4F:49:0D:FF:FF 98

2019 -05 -09 T14:58:40 daemon notice syslog: Send DHCP NACK to 00:4F:49:0D:FF:FF 90

 

Screenshots from wireshark:

1.JPG2.JPG3.JPG4.JPG

 

Any idea where is a problem for router?

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