DHCP: how devices obtain network settings

DHCP assigns local addressing parameters such as an IPv4 address, prefix information, default gateway and DNS servers. A lease has timers for renewal; expiry does not imply that every renewal changes the address.

What a device gets from DHCP

DHCP supplies a client with local network parameters such as an IP address, prefix or mask, default gateway and usually DNS servers. Those values are valid for a lease that the client renews periodically; renewal does not by itself mean the address must change.

How to check DHCP settings

Check the address, prefix, default gateway and DNS servers currently assigned to the interface, then compare them with the expected network. If the client has no lease or has fallen back to a link-local address, renew the lease and check whether DHCP traffic can reach the server or relay. To cross-check an address and prefix, use the 2ip IP calculator.

When an address is missing or keeps disappearing

Technical reference: RFC 2131.