Welcome to ExamTopics
ExamTopics Logo
- Expert Verified, Online, Free.

Unlimited Access

Get Unlimited Contributor Access to the all ExamTopics Exams!
Take advantage of PDF Files for 1000+ Exams along with community discussions and pass IT Certification Exams Easily.

Exam 301b topic 1 question 87 discussion

Actual exam question from F5's 301b
Question #: 87
Topic #: 1
[All 301b Questions]

The LTM device is configured to provide load balancing to a set of web servers that implement access control lists (ACL) based on the source IP address of the client. The ACL is at the network level and the web server is configured to send a TCP reset back to the client if it is NOT permitted to connect.
The virtual server is configured with the default OneConnect profile.
The ACL is defined on the web server as:

Permit: 192.168.136.0/24 -

Deny: 192.168.116.0/24 -
The packet capture is taken of two individual client flows to a virtual server with IP address 192.168.136.100.
Client A - Src IP 192.168.136.1 - Virtual Server 192.168.136.100:
Clientside:
09:35:11.073623 IP 192.168.136.1.55684 > 192.168.136.100.80: S 869998901:869998901(0) win 8192 <mss 1460,nop,wscale 2,nop,nop,sackOK>
09:35:11.073931 IP 192.168.136.100.80 > 192.168.136.1.55684: S 2273668949:2273668949(0) ack 869998902 win 4380 <mss 1460,nop,wscale 0,sackOK,eol>
09:35:11.074928 IP 192.168.136.1.55684 > 192.168.136.100.80: . ack 1 win 16425
09:35:11.080936 IP 192.168.136.1.55684 > 192.168.136.100.80: P 1:299(298) ack 1 win 16425
09:35:11.081029 IP 192.168.136.100.80 > 192.168.136.1.55684: . ack 299 win 4678
Serverside:
09:35:11.081022 IP 192.168.136.1.55684 > 192.168.116.128.80: S 685865802:685865802(0) win 4380 <mss 1460,nop,wscale 0,sackOK,eol>
09:35:11.081928 IP 192.168.116.128.80 > 192.168.136.1.55684: S 4193259095:4193259095(0) ack 685865803 win 5840 <mss
1460,nop,nop,sackOK,nop,wscale 6>
09:35:11.081943 IP 192.168.136.1.55684 > 192.168.116.128.80: . ack 1 win 4380
09:35:11.081955 IP 192.168.136.1.55684 > 192.168.116.128.80: P 1:299(298) ack 1 win 4380
09:35:11.083765 IP 192.168.116.128.80 > 192.168.136.1.55684: . ack 299 win 108
Client B - Src IP 192.168.116.1 - Virtual Server 192.168.136.100:
Clientside:
09:36:11.244040 IP 192.168.116.1.55769 > 192.168.136.100.80: S 3320618938:3320618938(0) win 8192 <mss 1460,nop,wscale 2,nop,nop,sackOK>
09:36:11.244152 IP 192.168.136.100.80 > 192.168.116.1.55769: S 3878120666:3878120666(0) ack 3320618939 win 4380 <mss 1460,nop,wscale
0,sackOK,eol>
09:36:11.244839 IP 192.168.116.1.55769 > 192.168.136.100.80: . ack 1 win 16425
09:36:11.245830 IP 192.168.116.1.55769 > 192.168.136.100.80: P 1:299(298) ack 1 win 16425
09:36:11.245922 IP 192.168.136.100.80 > 192.168.116.1.55769: . ack 299 win 4678
Serverside:
09:36:11.245940 IP 192.168.136.1.55684 > 192.168.116.128.80: P 599:897(298) ack 4525 win 8904
09:36:11.247847 IP 192.168.116.128.80 > 192.168.136.1.55684: P 4525:5001(476) ack 897 win 142
Why was the second client flow permitted by the web server?

  • A. A global SNAT is defined.
  • B. SNAT automap was enabled on the virtual server.
  • C. The idle TCP session from the first client was re-used.
  • D. A source address persistence profile is assigned to the virtual server.
Show Suggested Answer Hide Answer
Suggested Answer: C 🗳️

Comments

Chosen Answer:
This is a voting comment (?) , you can switch to a simple comment.
Switch to a voting comment New
GVKD
2 months, 2 weeks ago
B - Correct SNAT changes Client IP to 192.168.136.0/24 range.
upvoted 1 times
...
Melnikov
3 years, 6 months ago
Maybe because same TCP source port on server side are used...?
upvoted 1 times
...
Wassu
3 years, 6 months ago
Why not B
upvoted 3 times
SimonR2
2 years, 8 months ago
It’s not B because SNAT auto map is not enabled. You can see the client IP is preserved on the server side, it’s not using a self IP
upvoted 1 times
SimonR2
2 years, 8 months ago
Sorry, it looks like it does after all! The IP on the server side is snatted which is why it’s allowed through.
upvoted 1 times
...
...
...
Community vote distribution
A (35%)
C (25%)
B (20%)
Other
Most Voted
A voting comment increases the vote count for the chosen answer by one.

Upvoting a comment with a selected answer will also increase the vote count towards that answer by one. So if you see a comment that you already agree with, you can upvote it instead of posting a new comment.

SaveCancel
Loading ...