Your ACL is correct for udp/53, which is the port that most DNS resolution occurs on. While DNS queries normally run over UDP/53, they can also run over TCP/53. If a DNS A-record has over (approximately) 17 IP addresses, it will exceed the size of one DNS UDP packet and normal DNS resolution will use tcp/53.

Sep 28, 2010 · The above ACL only permits inbound DNS traffic on port 53 to host x.x.x.x (which is going to be the public IP assigned to the DNS server). Now, Referring to the ACL, you should specify all other traffic that should be permitted.

Sep 20, 2024 · Access Control Lists (ACLs) define allowed source IP addresses from where servers accept incoming data or control messages. When setting up new DNS zone transfers (incoming or outgoing), you will need to update the ACL at your other DNS provider (s) to allow Cloudflare to communicate with their server (s).

Jun 16, 2011 · Starting in ASA version 8.4 (2) (Feature not available in 8.5 (1) code) , ACL entries can contain a new type of object that represents a fully qualified domain-name. This allows administrators to create ACL entries that contain a new object type fqdn that …

Feb 26, 2024 · DNS BIND acl clause. This section describes the use of the acl (Access Control List) clause available in BIND 9.x named.conf. The acl clause allows fine-grained control over what hosts or users may perform what operations on the name server. acl clause syntax acl acl-name { address_match_list};

Mar 16, 2023 · acl enforces access control policies on source ip and prevents unauthorized access to DNS servers. With acl enabled, users are able to block or filter suspicious DNS queries by configuring IP filter rule sets, i.e. allowing authorized queries or blocking unauthorized queries.

Jan 28, 2025 · The command syntax format of a standard ACL is access-list access-list-number {permit|deny} {host|source source-wildcard|any}. Standard ACLs compare the source address of the IP packets to the addresses configured in the ACL in order to control traffic.

Mar 28, 2023 · With DNS-based ACLs, the client when in registration phase is allowed to connect to the configured URLs. The controller is configured with the ACL name that is returned by the AAA server. If the ACL name is returned by the AAA server, then the ACL is applied to the client for web-redirection.

To enable DNS-based ACLs on the embedded wireless controller, you need to configure the allowed URLs or denied URLs for the ACLs. The URLs need to be pre-configured on the ACL. With DNS-based ACLs, the client when in registration phase is allowed to connect to the configured URLs.

Jun 11, 2019 · Your ACL currently permits any UDP to 192.0.2.1 port 53 and everything from UDP port 53 to 192.0.2.1. If you want to deny any DNS access except for 192.0.2.1 you'd need access-list 112 permit udp any host 192.0.2.1 eq domain access-list 112 deny udp any any eq domain