mediumMultiple Choice
SNMPv2c Community Configuration — Common Mistakes
snmp-server community public RO\nsnmp-server community private RW\nsnmp-server community secret RW
What is wrong with this configuration?
Quick Answer
The answer is that the configuration lacks any access list to restrict SNMP access, which is the primary mistake. While having multiple read-write communities like "private" and "secret" is technically allowed, it introduces unnecessary security risk; however, the critical flaw is that without an access list applied to any of the snmp-server community statements, SNMPv2c traffic is accepted from any source IP address. On the Cisco CCNP ENARSI 300-410 exam, this tests your understanding that SNMPv2c community strings are essentially passwords sent in plaintext, and without ACL-based source filtering, the device is exposed to unauthorized read or write operations from the entire network. A common trap is focusing only on the duplication of RW communities and missing the missing ACL, so always check for the access-list keyword after the community string. Memory tip: “No ACL, no control — SNMP is open to all.”
⚠ Common exam trap
Cisco often tests the misconception that multiple RW communities are invalid or that community strings have a minimum length, when the real issue is the missing ACL to enforce source-based security.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
There is no access list to restrict SNMP access.
The configuration lacks an access control list (ACL) to restrict which SNMP managers can use the community strings. Without an ACL, any device that can reach the router can query or modify the SNMP agent using the 'public' or 'private' strings, creating a severe security vulnerability. Cisco SNMP best practices mandate that each community string should be paired with an ACL to limit source IP addresses.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
There is no access list to restrict SNMP access.
Why this is correct
Each snmp-server community entry lacks an access list argument, so any host that knows the community string can query or modify the device; restricting SNMP access to management hosts requires appending an ACL to each community statement.
- ✗
The community strings must be at least 8 characters.
Why it's wrong here
Cisco IOS imposes no minimum length on SNMP community strings, so short values such as public and private are accepted syntactically. It is tempting because weak, guessable strings are a genuine security weakness, but length is a hardening recommendation, not a configuration error.
- ✗
Only one read-write community is allowed.
Why it's wrong here
IOS permits multiple read-write community strings to coexist in the running configuration, so private and secret can both be defined. It is tempting because duplicate privileges look redundant, yet the device accepts them; the actual fault lies elsewhere in the listed commands.
- ✗
The 'public' community should be read-write.
Why it's wrong here
Read-only is the conventional and safest privilege for the public community string, so granting it RO is correct rather than wrong. It is tempting because public implies unrestricted access, but SNMP best practise deliberately restricts that community to read-only.
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Same concept, more angles
2 more ways this is tested on 300-410
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. snmp-server community public RO\nsnmp-server community private RW\nsnmp-server location DataCenter\nsnmp-server contact admin@example.com What is the effect of this configuration?
medium- A.SNMPv3 is enabled with authentication.
- ✓ B.SNMPv2c is enabled with read-only community 'public' and read-write community 'private'.
- C.Only read-only access is allowed using the 'private' community.
- D.SNMP traps are enabled to the location DataCenter.
Why B: The configuration uses SNMPv2c community strings 'public' (read-only) and 'private' (read-write), which are plain-text authentication mechanisms. SNMPv2c is enabled by default when community strings are configured, and the 'RO' and 'RW' keywords explicitly define the access levels. This matches option B exactly.
Variation 2. snmp-server community MyCommunity RO 10\naccess-list 10 permit 192.168.1.0 0.0.0.255 What is the effect of this configuration?
medium- ✓ A.SNMP read-only access is allowed only from the 192.168.1.0/24 subnet.
- B.SNMP read-write access is allowed from any host.
- C.SNMP access is allowed from any host, but only read-only.
- D.The community string is encrypted in the configuration.
Why A: The configuration `snmp-server community MyCommunity RO 10` sets the community string to 'MyCommunity' with read-only (RO) privileges and applies access-list 10. The `access-list 10 permit 192.168.1.0 0.0.0.255` restricts SNMP access to only the 192.168.1.0/24 subnet. Therefore, only hosts in that subnet can query the SNMP agent with read-only access.
JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This 300-410 practice question is part of Courseiva's free Cisco certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the 300-410 exam.