You are attempting to establish an IPsec VPN between two SRX devices. However, there is
another device between the SRX devices that does not pass traffic that is using UDP port 4500.
How would you resolve this problem?

A.
Enable NAT-T.

B.
Disable NAT-T.

C.
Disable PAT.

D.
Enable PAT.

Explanation:

NAT-T also uses UDP port 4500 (by default) rather than the standard UDP. So disabling NAT-T
will resolve this issue.
Reference :
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