I need to discover which DNS server(s) the LAN DHCP server (usually the router) gives to clients, without changing any DHCP state.

Approach

1. Send a single DHCP Discover that requests Parameter 6 (DNS servers) in the Parameter Request List (Option 55).

2. Include Option 50 (Requested IP) set to this device’s current DHCP‑leased address.

3. Listen for the DHCP Offer and parse Option 6 (DNS servers) from it.

4. Do not send DHCP Request or use the offered lease in any way — i.e. never complete DORA (Discover → Offer → Request → Acknowledge).

Intended safety

• Per RFC 2131, a lease is committed when the client sends Request and the server sends Ack. Since we only send Discover and never Request, we expect no lease to be committed for our client identifier (e.g. MAC).

• The server might temporarily reserve an address until the offer times out (e.g. 60–120 seconds), after which it should return to the pool.

• We send this rarely (every 24 hours).

Question

Is it safe to assume that this pattern (Discover only, no Request, low rate) does not commit a lease and does not cause problems on typical networks? Are there real-world DHCP implementations or network setups (e.g. strict pools, relay agents, or non‑RFC behavior) where this could still cause issues (e.g. lease exhaustion, stuck reservations, or other side effects)?