Refer to the exhibit. Which SPF record is valid for mycompany.com?

The correct answer is C. v=spf1 a mx ip4:199.209.31.21 -all. An SPF (Sender Policy Framework) record must list the actual public IP address of the authorized outbound mail server for the domain. In the referenced exhibit, 199.209.31.21 is the legitimate public/external IP address assigned to mycompany.com's mail server. Option B…

Email Authentication and Encryption

Question

Exhibit

Options

Av=spf1 a mx ip4:199.209.31.2 -all
Bv=spf1 a mx ip4:10.1.10.23 -all
Cv=spf1 a mx ip4:199.209.31.21 -all
Dv=spf1 a mx ip4:172.16.18.230 -all

How the community answered

(31 responses)

A
10% (3)
B
3% (1)
C
71% (22)
D
16% (5)

Explanation

An SPF (Sender Policy Framework) record must list the actual public IP address of the authorized outbound mail server for the domain. In the referenced exhibit, 199.209.31.21 is the legitimate public/external IP address assigned to mycompany.com's mail server. Option B (10.1.10.23) is a private RFC 1918 address and should not appear in a public DNS SPF record. Option D (172.16.18.230) is also a private address. Option A (199.209.31.2) is a public IP but does not match the correct server address shown in the exhibit. The '-all' mechanism means all senders not listed are unauthorized (hard fail).

Topics

#SPF#Email Authentication#DNS Records#Email Security

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