Among the following types of LSA, the ones allowed in the backbone area are _________

Imperative for canceling RIP auto-route aggregation on MSR routers

In the broadcast network of OSPF, there are 4 routers RTA, RTB, RTC and RTD in the same network segment, their priorities are 2, 0, 1 and 1 respectively, and the Router IDs are 192.168.1.1, 192.168.2.1, 192.168 respectively. 3.1 and 192.168.4.1.
If the OSPF protocol is activated on these four routers at the same time, the BDR selected by OSPF is _____.

If fast forwarding is enabled on the router, when the first packet of the data flow arrives on the interface, which of the following actions will be performed?

Running the command on the router and its display information is as follows:
<RTC>displisis lsdb level-2 verbose
Database information for ISIS(1)
--------------------------------
Level-2 Link State Database
LSPID Se Num Checksum Holdtime Length ATT/P/OL
-------------------------------------------------- -----------------------------
1111.1111.1111.00-00 0x00000084 0xb5cc 511 62 0/0/0
SOURCE 1111.1111.1111.00
NLPID IPV4
AREA ADDR 01
INTF ADDR 10.1.2.1
INTF ADDR 10.1.3.1
INTF ADDR 172.16.3.1
NBR ID 3333.3333.3333.00 COST: 10
1111.1111.1111.00-01 0x0000009f 0xd4f3 1195 101 0/0/0
SOURCE 1111.1111.1111.00
IP-Internal 10.2.4.0 255.255.255.252 COST: 20
IP-Internal 192.168.18.0 255.255.255.0 COST: 20
IP-Internal 10.1.2.0 255.255.255.252 COST: 10
IP-Internal 10.1.3.0 255.255.255.252 COST: 10
IP-Internal 172.16.3.1 255.255.255.255 COST: 0
IP-Internal 172.16.0.0 255.255.252.0 COST: 10
3333.3333.3333.00-00* 0x0000007c 0x2425 640 58 0/0/0
SOURCE 3333.3333.3333.00
NLPID IPV4
AREA ADDR 02
INTF ADDR 10.1.3.2
INTF ADDR 10.3.4.1
NBR ID 1111.1111.1111.00 COST: 10
3333.3333.3333.00-01* 0x00000099 0x342d 640 77 0/0/0
SOURCE 3333.3333.3333.00
IP-Internal 10.1.3.0 255.255.255.252 COST: 10
IP-Internal 10.3.4.0 255.255.255.252 COST: 10
IP-Internal 10.2.4.0 255.255.255.252 COST: 20
IP-Internal 172.16.4.1 255.255.255.255 COST: 10
*-Self LSP, +-Self LSP(Extended), ATT-Attached, P-Partition, OL-Overload
From the above information, we can know that __________.