SPLITDNS.CONFIG(5)

💖 SPLITDNS.CONFIG(5) 💖

okay bestie, gather round, because this is the splitdns.config page from the Apache Traffic Server manual and it's genuinely one of my faves. it's a 5 in section 5, which means it's a config file page, iykyk 🎀

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✨ NAME ✨

so splitdns.config is the Traffic Server split DNS configuration file. that's the whole vibe.

what it does: it lets you tell Traffic Server which DNS server it should use for resolving hosts under specific conditions. want the full lore? go read Split DNS, fr fr.

to actually specify a DNS server, you HAVE to hand over this info on every active line in the file, no skipping:

• a primary destination specifier, which comes in the form of a destination domain, a destination host, or a URL regular expression
• a set of server directives, listing one or more DNS servers with their corresponding port numbers

and you can also toss in this optional stuff with each DNS server specification:

• a default domain for resolving hosts
• a search list that specifies the domain search order when multiple domains are specified

🫶 real talk: after you modify the splitdns.config file, run the traffic_ctl config reload command to apply the changes. don't forget, bestie, or nothing happens and you'll be staring at your terminal like 😭

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🌸 FORMAT 🌸

every line in the splitdns.config file uses one of these formats:

dest_domain=dest_domain | dest_host | url_regex named=dns_server def_domain=def_domain search_list=search_list

here's the breakdown of every field, one by one, because we do not gatekeep 💅

• dest_domain — a valid domain name. this says DNS server selection is gonna be based on the destination domain. you can prefix the domain with an exclamation mark (!) to indicate the NOT logical operator.
• dest_host — a valid hostname. this says DNS server selection will be based on the destination host. you can prefix the host with an exclamation mark (!) to indicate the NOT logical operator.
• url_regex — a valid URL regular expression. this says DNS server selection will be based on a regular expression.
• named — this one is a required directive, no cap. it identifies the DNS server that Traffic Server should use with the given destination specifier. you can specify a port using a colon (:). if you do not specify a port, then 53 is used. specify multiple DNS servers with spaces or semicolons (;) as separators.

👑 heads up: you must specify the domains with IP addresses in CIDR ("dot") notation.

• def_domain — a valid domain name. this optional directive specifies the default domain name to use for resolving hosts. only one entry is allowed. if you do not provide the default domain, the system determines its value from /etc/resolv.conf
• search_list — a list of domains separated by spaces or semicolons (;). this specifies the domain search order. if you do not provide the search list, the system determines the value from resolv.conf(5)

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🦋 EXAMPLES 🦋

okay so consider these DNS server selection specifications:

dest_domain=internal.company.com named="255.255.255.255:212 255.255.255.254" def_domain=company.com search_list="company.com company1.com"
dest_domain=!internal.company.com named=255.255.255.253

now consider these two requests, because this is where it gets good:

http://minstar.internal.company.com

this request matches the first line and therefore selects DNS server 255.255.255.255 on port 212. all resolver requests use company.com as the default domain, and company.com and company1.com as the set of domains to search first. slay ✨

http://www.microsoft.com

this request matches the second line. therefore, Traffic Server selects DNS server 255.255.255.253. because no def_domain or search_list was supplied, Traffic Server retrieves this information from resolv.conf(5). it's giving self-sufficient 💀

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🎀 COPYRIGHT 🎀

2026, dev@trafficserver.apache.org

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and that's the whole page, bestie, no notes 🫶 this was the SPLITDNS.CONFIG(5) page, version 9.2, dated Feb 12, 2026. go forth and resolve hosts correctly, you absolute icon 💖🌸🦋