Do headers change when a message is sent from point A to point B through several intermediate routers?

Question

Network administration

Hello. When sending a message from the start point (S) to the end point (D) through intermediate routers (R), as in the figure, do:
1) TTL in the IP header
2) Sequence number in the TCP header
3) Destination MAC address in the Ethernet header
4) checksum in IP header
5) destination IP address?

Answer 1

1. Must, but not required (transparent firewalls and routers are set up so as not to reduce the TTL past passing traffic)
   
2. No (session has nothing to do with routing)
   
3. Changes on every hop between any devices (same as source MAC)
   
4. Changes along with TTL (thanks to Andrey for the clarification)
   
5. No (routing is carried out on it, there is no point in changing it)
   

Answer 2

1 changes
2 does not change
3 not sure, but seems to change
4 does not change
5 does not change